Interview Based Question AD DNS FSMO GPO1

7/31/2019 Interview Based Question AD DNS FSMO GPO1

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ACTIVE DIRECTORY DNS FSMO GROUP POLICY

What Is Active Directory?

Active Directory consists of a series of components that constitute both its logicalstructure and its physical structure. It provides a way for organizations to centrally

manage and store their user objects, computer objects, group membership, anddefine security boundaries in a logical database structure.

Purpose of Active Directory

Active Directory stores information about users, computers, and network resourcesand makes the resources accessible to users and applications. It provides aconsistent way to name, describe, locate, access, manage, and secure informationabout these resources

Functions of Active Directory

Active Directory provides the following functions:

Centralizes control of network resourcesBy centralizing control of resources such as servers, shared files, and printers,only authorized users can access resources in Active Directory.

Centralizes and decentralizes resource managementAdministrators have Centralized Administration with the ability to delegateadministration of subsets of the network to a limited number of individuals givingthem greater granularity in resource management.

Store objects securely in a logical structureActive Directory stores all of the resources as objects in a secure, hierarchicallogical structure.

Optimizes network trafficThe physical structure of Active Directory enables you to use network bandwidthmore efficiently. For example, it ensures that, when users log on to the network,the authentication authority that is nearest to the user, authenticates themreducing the amount of network traffic.

Sites within Active Directory

Sites are defined as groups of well-connected computers. When you establish sites, domaincontrollers within a single site communicate frequently. This communication minimizes thelatency within the site; that is, the time required for a change that is made on one domaincontroller to be replicated to other domain controllers. You create sites to optimize the use ofbandwidth between domain controllers that are in different locations

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Operations Master Roles

When a change is made to a domain, the change is replicated across all of thedomain controllers in the domain. Some changes, such as those made to the schema,are replicated across all of the domains in the forest. This replication is called

multimaster replication.During multimaster replication, a replication conflict can occur if originating updatesare performed concurrently on the same object attribute on two domain controllers. Toavoid replication conflicts, Active Directory uses single master replication, whichdesignates one domain controller as the only domain controller on which certaindirectory changes can be made. This way, changes cannot occur at different places inthe network at the same time. Active Directory uses single master replication forimportant changes, such as the addition of a new domain or a change to the forest-wide schema.

Operations that use single-master replication are arranged together in specific roles in

a forest or domain. These roles are called operations master roles. For eachoperations master role, only the domain controller that holds that role can make theassociated directory changes. The domain controller that is responsible for a particularrole is called an operations master for that role. Active Directory stores informationabout which domain controller holds a specific role.

Forest-wide Roles

Forest-wide roles are unique to a forest, forest-wide roles are:

Schema masterControls all updates to the schema. The schema contains the master list of objectclasses and attributes that are used to create all Active Directory objects, such asusers, computers, and printers.

Domain naming masterControls the addition or removal of domains in the forest. When you add a newdomain to the forest, only the domain controller that holds the domain namingmaster role can add the new domain.

There is only one schema master and one domain naming master in the entire forest.

Domain-wide Roles

Domain-wide roles are unique to each domain in a forest, the domain-wide roles are:

Primary domain controller emulator (PDC)Acts as a Windows NT PDC to support any backup domain controllers (BDCs)running Microsoft Windows NT within a mixed-mode domain. This type ofdomain has domain controllers that run Windows NT 4.0. The PDC emulator is thefirst domain controller that you create in a new domain.

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Relative identifier master (RID)When a new object is created, the domain controller creates a new securityprincipal that represents the object and assigns the object a unique securityidentifier (SID). This SID consists of a domain SID, which is the same for allsecurity principals created in the domain, and a RID, which is unique for eachsecurity principal created in the domain. The RID master allocates blocks of RIDsto each domain controller in the domain. The domain controller then assigns aRID to objects that are created from its allocated block of RIDs.

Infrastructure masterwhen objects are moved from one domain to another, the infrastructure masterupdates object references in its domain that point to the object in the otherdomain. The object reference contains the objects globally unique identifier(GUID), distinguished name, and a SID. Active Directory periodically updates thedistinguished name and the SID on the object reference to reflect changes madeto the actual object, such as moves within and between domains and the deletionof the object.

The global catalog contains:

The attributes that are most frequently used in queries, such as a users firstname, last name, and logon name.

The information that is necessary to determine the location of any object in thedirectory.

The access permissions for each object and attribute that is stored in the globalcatalog. If you search for an object that you do not have the appropriatepermissions to view, the object will not appear in the search results. Accesspermissions ensure that users can find only objects to which they have been

assigned access.A global catalog server is a domain controller that, in addition to its full, writabledomain directory partition replica, also stores a partial, read-only replica of all otherdomain directory partitions in the forest. Taking a user object as an example, it wouldby default have many different attributes such as first name, last name, phonenumber, and many more. The GC will by default only store the most common of thoseattributes that would be used in search operations (such as a users first and lastnames, or login name, for example). The partial attributes that it has for that objectwould be enough to allow a search for that object to be able to locate the full replica ofthe object in active directory. This allows searches done against a local GC, andreduces network traffic over the WAN in an attempt to locate objects somewhere else

in the network.

Domain Controllers always contain the full attribute list for objects belonging to theirdomain. If the Domain Controller is also a GC, it will also contain a partial replica ofobjects from all other domains in the forest.

Active Directory uses DNS as the name resolution service to identify domains anddomain host computers during processes such as logging on to the network.

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Similar to the way a Windows NT 4.0 client will query WINS for a NetBIOSDOMAIN[1B] record to locate a PDC, or a NetBIOS DOMAIN[1C] record for domaincontrollers, a Windows 2000, 2003, or Windows XP client can query DNS to find adomain controller by looking for SRV records.

Integration of DNS and Active Directory

The integration of DNS and Active Directory is essential because a client computer ina Windows 2000 network must be able to locate a domain controller so that users canlog on to a domain or use the services that Active Directory provides. Clients locatedomain controllers and services by using A resource records and SRV records. The Aresource record contains the FQDN and IP address for the domain controller. TheSRV record contains the FQDN of the domain controller and the name of the servicethat the domain controller provides.

What Are Active Directory Integrated Zones?One benefit of integrating DNS and Active Directory is the ability to integrate DNSzones into an Active Directory database. A zone is a portion of the domainnamespace that has a logical grouping of resource records, which allows zonetransfers of these records to operate as one unit.

Active Directory Integrated Zones

Microsoft DNS servers store information that is used to resolve host names to IPaddresses and IP addresses to host names in a database file that has the extension.dns for each zone.

Active Directory integrated zones are primary zones that are stored as objects in theActive Directory database. If zone objects are stored in an Active Directory domainpartition, they are replicated to all domain controllers in the domain.

What Are DNS Zones?

A zone starts as a storage database for a single DNS domain name. If other domainsare added below the domain used to create the zone, these domains can either bepart of the same zone or belong to another zone. Once a subdomain is added, it can

then either be: Managed and included as part of the original zone records, or

Delegated away to another zone created to support the subdomain

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Types of Zones

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There are two types of zones, forward lookup and reverse lookup. Forward lookupzones contain information needed to resolve names within the DNS domain. Theymust include SOA and NS records and can include any type of resource record exceptthe PTR resource record. Reverse lookup zones contain information needed toperform reverse lookups. They usually include SOA, NS, PTR, and CNAME records.

With most queries, the client supplies a name and requests the IP address thatcorresponds to that name. This type of query is typically described as a forwardlookup. Active Directory requires forward lookup zones.

However, what if a client already has a computer's IP address and wants to determinethe DNS name for the computer? This is important for programs that implementsecurity based on the connecting FQDN, and is used for TCP/IP networktroubleshooting. The DNS standard provides for this possibility through reverselookups.

Once you have installed Active Directory, you have two options for storing your zones

when operating the DNS server at the new domain controller:

Standard Zone

Zones stored this way are located in .dns text files that are stored in the%SystemRoot%\System32\Dns folder on each computer operating a DNS server.Zone file names correspond to the name you choose for the zone when creating it,such as Example.microsoft.com.dns if the zone name wasexample.microsoft.com.

This type offers the choice of using either a Standard Primary zone or a StandardSecondary zone.

Standard Primary Zone

For standard primary-type zones, only a single DNS server can host and load themaster copy of the zone. If you create a zone and keep it as a standard primary zone,no additional primary servers for the zone are permitted. Only one server is allowed toaccept dynamic updates, also known as DDNS, and process zone changes. Thestandard primary model implies a single point of failure.

Standard Secondary Zone

A secondary name server gets the data for its zones from another name server (eithera primary name server or another secondary name server) for that zone across the

network. The data in a Secondary zone is Read only, and updated information mustcome from additional zone transfers. The process of obtaining this zone information(i.e., the database file) across the network is referred to as a zone transfer. Zonetransfers occur over TCP port 53.

Secondary servers can provide a means to offload DNS query traffic in areas of thenetwork where a zone is heavily queried and used. Additionally, if a primary server isdown, a secondary server can provide some name resolution in the zone until theprimary server is available.

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Note A Standard Primary zone will not replicate its information to any other DNSservers, but may allow zone transfers to Secondary zones. Win2003 also supportsstub zones. A secondary or stub zone cannot be hosted on a DNS server thathosts a primary zone for the same domain name.

Directory-integrated ZoneZones stored this way are located in the Active Directory tree under the domain objectcontainer. Each directory-integrated zone is stored in a dnsZone container objectidentified by the name you choose for the zone when creating it. Active Directoryintegrated zones will replicate this information to other domain controllers in thatdomain.

Note If DNS is running on a Windows 2000 server that is not a domain controller, it willnot be able to use an Active Directory integrated zones, or replicate with otherdomain controllers since it does not have Active Directory installed.

DNS Records

After you create a zone, additional resource records need to be added to it. The mostcommon resource records (RRs) to be added are:

Table 1. Record Types

Name Description

Host (A) For mapping a DNS domain name to an IP address used by acomputer.

Alias (CNAME) For mapping an alias DNS domain name to another primary orcanonical name.

Mail Exchanger(MX)

For mapping a DNS domain, name to the name of a computer thatexchanges or forwards mail.

Pointer (PTR) For mapping a reverse DNS domain name based on the IP address ofa computer that points to the forward DNS domain name of thatcomputer.

Service location(SRV)

For mapping a DNS domain name to a specified list of DNS hostcomputers that offer a specific type of service, such as Active Directorydomain controllers.

Other resource records as needed.

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Q1. What does the logical component of the Active Directory structure include?

Objects:-Resources are stored in the Active Directory as objects.

Sub category: object class

An object is really just a collection of attributes. A user object, for example, is made up ofattributes such as name, password, phone number, group membership, and so on. The

attributes that make up an object are defined by an object class. The user class, for example,specifies the attributes that make up the user object.

The Active Directory Schema:-

The classes and the attributes that they define are collectively referred to as the ActiveDirectory Schemain database terms, a schema is the structure of the tables and fields andhow they are related to one another. You can think of the Active Directory Schema as acollection of data (object classes) that defines how the real data of the directory (the attributesof an object) is organized and stored

Domains

The basic organizational structure of the Windows Server 2003 networking model is thedomain. A domain represents an administrative boundary. The computers, users, and otherobjects within a domain share a common security database.

Trees

Multiple domains are organized into a hierarchical structure called a tree. Actually, even if youhave only one domain in your organization, you still have a tree. The first domain you create in

a tree is called the root domain. The next domain that you add becomes a child domain of thatroot. This expandability of domains makes it possible to have many domains in a tree. Figure1-1 shows an example of a tree. Microsoft.com was the first domain created in ActiveDirectory in this example and is therefore the root domain.

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Microsoft.com

sales.microsoft.co RND.Microsoft.com

West.Microsoft.comEast.Microsoft.com


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Figure 1-1 A tree is a hierarchical organization of multiple domains.All domains in a tree share a common schema and a contiguous namespace. In the exampleshown in Figure 1-1, all of the domains in the tree under the microsoft.com root domain sharethe namespace microsoft.com. Using a single tree is fine if your organization is confined withina single DNS namespace. However, for organizations that use multiple DNS namespaces,your model must be able to expand outside the boundaries of a single tree. This is where theforest comes in.

Forest

A forest is a group of one or more domain trees that do not form a contiguous namespace butmay share a common schema and global catalog. There is always at least one forest on anetwork, and it is created when the first Active Directoryenabled computer (domain controller)on a network is installed.

This first domain in a forest, called the forest root domain, is special because it holds theschema and controls domain naming for the entire forest. It cannot be removed from the forestwithout removing the entire forest itself. Also, no other domain can ever be created above the

forest root domain in the forest domain hierarchy.

Figure 1-2 shows an example of a forest with two trees. Each tree in the forest has its ownnamespace. In the figure, microsoft.com is one tree and contoso.com is a second tree. Bothare in a forest named microsoft.com (after the first domain created)

Figure 1-2 Trees in a forest share the same schema, but not the same namespace.

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Microsoft.com

sales.microsoft.co RND.Microsoft.com

West.Microsoft.comEast.Microsoft.com

Root domain of

microsoft.com

forest & tree

Contoso.com

West.contoso.com

East.contoso.com

Root domain of

Contoso.com


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A forest is the outermost boundary of Active Directory; the directory cannot be larger than theforest. However, you can create multiple forests and then create trust relationships betweenspecific domains in those forests; this would let you grant access to resources and accountsthat are outside of a particular forest.

Organizational Units

Organizational Units (OUs) provide a way to create administrative boundaries within a domain.Primarily, this allows you to delegate administrative tasks within the domain.

OUs serve as containers into which the resources of a domain can be placed. You can thenassign administrative permissions on the OU itself. Typically, the structure of OUs follows anorganizations business or functional structure. For example, a relatively small organizationwith a single domain might create separate OUs for departments within the organization.

Q2. What does the physical structure of active directory contain?

Physical structures include domain controllers and sites.

Q3.What is nesting?

The creation of an OU inside another OU.

IMP: - once you go beyond about 12 OUs deep in a nesting structure, you start running intosignificant performance issues.

Q4. What is trust relationship and how many types of trust relationship is there inexchange 2003?

Since domains represent security boundaries, special mechanisms called trust relationshipsallow objects in one domain (called the trusted domain) to access resources in anotherdomain (called the trusting domain).

Windows Server 2003 supports six types of trust relationships:

Parent and child trusts

Tree-root trusts External trusts Shortcut trusts Realm trusts Forest trusts

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Q5. What is a site?

A Windows Server 2003 site is a group of domain controllers that exist on one or more IPsubnets (see Lesson 3 for more on this) and are connected by a fast, reliable networkconnection. Fast means connections of at least 1Mbps. In other words, a site usually followsthe boundaries of a local area network (LAN). If different LANs on the network are connectedby a wide area network (WAN), youll likely create one site for each LAN.

Q6. What is the use of site?

Sites are primarily used to control replication traffic. Domain controllers within a site are prettymuch free to replicate changes to the Active Directory database whenever changes are made.Domain controllers in different sites compress the replication traffic and operate based on adefined schedule, both of which are intended to cut down on network traffic.

More specifically, sites are used to control the following:

Workstation logon traffic

Replication traffic Distributed File System (DFS)

Distributed File System (DFS) is a server component that provides a unified namingconvention for folders and files stored on different servers on a network. DFS lets you create asingle logical hierarchy for folders and files that is consistent on a network, regardless ofwhere on the network those items are actually stored. Files represented in the DFS might bestored in multiple locations on the network, so it makes sense that Active Directory should beable to direct users to the closest physical location of the data they need. To this end, DFSuses site information to direct a client to the server that is hosting the requested data withinthe site. If DFS does not find a copy of the data within the same site as the client, DFS uses

the site information in Active Directory to determine which file server that has DFS shared datais closest to the client.

File Replication Service (FRS)

Every domain controller has a built-in collection of folders named SYSVOL (for SystemVolume). The SYSVOL folders provide a default Active Directory location for files that must bereplicated throughout a domain. You can use SYSVOL to replicate Group Policy Objects,startup and shutdown scripts, and logon and logoff scripts. A Windows Server 2003 servicenamed File Replication Service (FRS) is responsible for replicating files in the SYSVOL folders

between domain controllers. FRS uses site boundaries to govern the replication of items in theSYSVOL folders.

Q7. What are the objects a site contains?

Sites contain only two types of objects. The first type is the domain controllers contained in thesite. The second type of object is the site links configured to connect the site to other sites.

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Q8.What is a Site link?

Within a site, replication happens automatically. For replication to occur between sites, youmust establish a link between the sites. There are two components to this link: the actualphysical connection between the sites (usually a WAN link) and a site link object. The site linkobject is created within Active Directory and determines the protocol used for transferringreplication traffic (Internet Protocol [IP] or Simple Mail Transfer Protocol [SMTP]). The site link

object also governs when replication is scheduled to occur.

Q9. Explain Replication in Active directory?

Windows Server 2003 uses a replication model called multimaster replication, in which allreplicas of the Active Directory database are considered equal masters. You can makechanges to the database on any domain controller and the changes will be replicated to otherdomain controllers in the domain.

Domain controllers in the same site replicate on the basis of notification. When changes aremade on a domain controller, it notifies its replication partners (the other domain controllers in

the site); the partners then request the changes and replication occurs. Because of the high-speed, low-cost connections assumed within a site, replication occurs as needed rather thanaccording to a schedule.

You should create additional sites when you need to control how replication traffic occurs overslower WAN links. For example, suppose you have a number of domain controllers on yourmain LAN and a few domain controllers on a LAN at a branch location. Those two LANs areconnected to one another with a slow (256K) WAN link. You would want replication traffic tooccur as needed between the domain controllers on each LAN, but you would want to controltraffic across the WAN link to prevent it from affecting higher priority network traffic. Toaddress this situation, you would set up two sites one site that contained all the domain

controllers on the main LAN and one site that contained all the domain controllers on theremote LAN.

Q10. What are the different types of replication?

Single site (called intrasite replication)Replication between sites (called intersite replication).

Intrasite Replication Intrasite replication sends replication traffic in an uncompressed

format. This is because of the assumption that all domain controllers within the site areconnected by high-bandwidth links. Not only is the traffic uncompressed, but replication occursaccording to a change notification mechanism. This means that if changes are made in thedomain, those changes are quickly replicated to the other domain controllers.

Intersite Replication Intersite replication sends all data compressed. This shows anappreciation for the fact that the traffic will probably be going across slower WAN links (asopposed to the LAN connectivity intrasite replication assumes), but it increases the server loadbecause compression/decompression is added to the processing requirements. In addition tothe compression, the replication can be scheduled for times that are more appropriate to your

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organization. For example, you may decide to allow replication only during slower times of theday. Of course, this delay in replication (based on the schedule) can cause inconsistencybetween servers in different sites.

Q11. What is LDAP?

LDAP, Lightweight Directory Access Protocol, is an Internet protocol that email and otherprograms use to look up information from a server.

An LDAP-aware directory service (such as Active Directory) indexes all the attributes of all theobjects stored in the directory and publishes them. LDAP-aware clients can query the server ina wide variety of ways.

Q12.What types of naming convention active directory uses?

Active Directory supports several types of names for the different formats that canaccessActive Directory.These names include:

Relative Distinguished Names

The relative distinguished name (RDN) of an object identifies an object uniquely, but onlywithin its parent container. Thus the name uniquely identifies the object relative to the otherobjects within the same container. In the example

CN=wjglenn,CN=Users,DC=contoso,DC=com,

the relative distinguished name of the object is CN=wjglenn. The relative distinguished nameof the parent organizational unit is Users. For most objects, the relative distinguished name of

an object is the same as that objects Common Name attribute. Active Directory creates therelative distinguished name automatically, based on information provided when the object iscreated. Active Directory does not allow two objects with the same relative distinguished nameto exist in the same parent container.

The notations used in the relative distinguished name (and in the distinguished namediscussed in the next section) use special notations called LDAP attribute tags to identify eachpart of the name. The three attribute tags used include:

DC The Domain Component (DC) tag identifies part of the DNS name of the domain, suchas COM or ORG.

OU The Organizational Unit (OU) tag identifies an organizational unit container. CN The Common Name (CN) tag identifies the common name configured for an ActiveDirectory object.

Distinguished Names

Each object in the directory has a distinguished name (DN) that is globally unique andidentifies not only the object itself, but also where the object resides in the overall objecthierarchy. You can think of the distinguished name as the relative distinguished name of an

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object concatenated with the relative distinguished names of all parent containers that makeup the path to the object.

An example of a typical distinguished name would be:

CN=wjglenn,CN=Users,DC=contoso,DC=com.

This distinguished name would indicate that the user object wjglenn is in the Users container,

which in turn is located in the contoso.com domain. If the wjglenn object is moved to anothercontainer, its DN will change to reflect its new position in the hierarchy. Distinguished namesare guaranteed to be unique in the forest, similar to the way that a fully qualified domain nameuniquely identifies an objects placement in a DNS hierarchy. You cannot have two objectswith the same distinguished name.

User Principal Names

The user principal name that is generated for each object is in the form username@domain_name. Users can log on with their user principal name, and an administrator candefine suffixes for user principal names if desired. User principal names should be unique, but

Active Directory does not enforce this requirement. Its best, however, to formulate a namingconvention that avoids duplicate user principal names.

Canonical Names

An objects canonical name is used in much the same way as the distinguished name it justuses a different syntax. The same distinguished name presented in the preceding sectionwould have the canonical name:

contoso.com/Users/wjglenn.

As you can see, there are two primary differences in the syntax of distinguished names andcanonical names. The first difference is that the canonical name presents the root of the pathfirst and works downward toward the object name. The second difference is that the canonicalname does not use the LDAP attribute tags (e.g., CN and DC).

Q13. What is multimaster replication?

Active Directory follows the multimaster replication which every replica of the Active Directory

partition held on every domain is considered an equal master. Updates can be made toobjects on any domain controller, and those updates are then replicated to other domaincontrollers.

Q14.Which two operations master roles should be available when new securityprincipals are being created and named?

Domain naming master and the relative ID master

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Q15. What are different types of groups?

Security groups Security groups are used to group domain users into a singleadministrative unit. Security groups can be assigned permissions and can also be used as e-mail distribution lists. Users placed into a group inherit the permissions assigned to the groupfor as long as they remain members of that group. Windows itself uses only security groups.

Distribution groups These are used for nonsecurity purposes by applications other than

Windows. One of the primary uses is within an e-mail

As with user accounts, there are both local and domain-level groups. Local groups are storedin a local computers security database and are intended to control resource access on thatcomputer. Domain groups are stored in Active Directory and let you gather users and controlresource access in a domain and on domain controllers.

Q16. What is a group scope and what are the different types of group scopes?

Group scopes determine where in the Active Directory forest a group is accessible and whatobjects can be placed into the group. Windows Server 2003 includes three group scopes:

global, domain local, and universal.

Global groups are used to gather users that have similar permissions requirements. Globalgroups have the following characteristics:

1. Global groups can contain user and computer accounts only from the domain in which theglobal group is created.2. When the domain functional level is set to Windows 2000 native or Windows Server 2003(i.e., the domain contains only Windows 2000 or 2003 servers), global groups can also containother global groups from the local domain.3. Global groups can be assigned permissions or be added to local groups in any domain in a

forest.

Domain local groups exist on domain controllers and are used to control access toresources located on domain controllers in the local domain (for member servers andworkstations, you use local groups on those systems instead). Domain local groups share thefollowing characteristics:

1. Domain local groups can contain users and global groups from any domain in a forest nomatter what functional level is enabled.2. When the domain functional level is set to Windows 2000 native or Windows Server 2003,domain local groups can also contain other domain local groups and universal groups.

Universal groups are normally used to assign permissions to related resources in multipledomains. Universal groups share the following characteristics:

1. Universal groups are available only when the forest functional level is set to Windows 2000native or Windows Server 2003.2. Universal groups exist outside the boundaries of any particular domain and are managed byGlobal Catalog servers.3. Universal groups are used to assign permissions to related resources in multiple domains.

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4. Universal groups can contain users, global groups, and other universal groups from anydomain in a forest.5. You can grant permissions for a universal group to any resource in any domain.

Q17. What are the items that groups of different scopes can contain in mixed and nativemode domains?

Q18. What is group nesting?

Placing of one group in another is called as group nesting

For example, suppose you had juniorlevel administrators in four different geographic locations,as shown in Figure 4-10. You could create a separate group for each location (namedsomething like Dallas Junior

Admins). Then, you could create a single group named Junior Admins and make each of thelocation-based groups a member of the main group. This approach would allow you to setpermissions on a single group and have those permissions flow down to the members, yet stillbe able to subdivide the junior administrators by location.

Q19. How many characters does a group name contain?

64

Q20. Is site part of the Active Directory namespace?

NO: - When a user browses the logical namespace, computers and users are grouped intodomains and OUs without reference to sites. However, site names are used in the DomainName System (DNS) records, so sites must be given valid DNS names.

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Q21. What is DFS?

The Distributed File System is used to build a hierarchical view of multiple file servers andshares on the network. Instead of having to think of a specific machine name for each set offiles, the user will only have to remember one name; which will be the 'key' to a list of sharesfound on multiple servers on the network. Think of it as the home of all file shares with linksthat point to one or more servers that actually host those shares.

DFS has the capability of routing a client to the closest available file server by using ActiveDirectory site metrics. It can also be installed on a cluster for even better performance andreliability.

Understanding the DFS TerminologyIt is important to understand the new concepts that are part of DFS. Below is an definition ofeach of them.

Dfs root:You can think of this as a share that is visible on the network, and in this share youcan have additional files and folders.

Dfs link: A link is another share somewhere on the network that goes under the root. When auser opens this link they will be redirected to a shared folder.

Dfs target (or replica): This can be referred to as either a root or a link. If you have twoidentical shares, normally stored on different servers, you can group them together as DfsTargets under the same link.

The image below shows the actual folder structure of what the user sees when using DFS andload balancing.

Figure 1: The actual folder structure of DFS and load balancing

Windows 2003 offers a revamped version of the Distributed File System found in Windows2000, which has been improved to better performance and add additional fault tolerance, loadbalancing and reduced use of network bandwidth. It also comes with a powerful set of

command-line scripting tools which can be used to make administrative backup andrestoration tasks of the DFS namespaces easier. The client windows operating systemconsists of a DFS client which provides additional features as well as caching.

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Q22. What are the types of replication in DFS?

There are two types of replication:* Automatic - which is only available for Domain DFS* Manual - which is available for stand alone, DFS and requires all files to be replicatedmanually.

Q23. Which service is responsible for replicating files in SYSVOL folder?

File Replication Service (FRS)

Q24. What all can a site topology owner do?

The site topology owner is the name given to the administrator (or administrators) that overseethe sitetopology. The owner is responsible for making any necessary changes to the site as thephysical network grows and changes. The site topology owners responsibilities include:

Making changes to the site topology based on changes to the physical network topology. Tracking subnetting information for the network. This includes IP addresses, subnet masks,and the locations of the subnets. Monitoring network connectivity and setting the costs for links between sites.

Q1. What is DNS.

DNS provides name registration and name to address resolution capabilities. And DNSdrastically lowers the need to remember numeric IP addresses when accessing hosts on theInternet or any other TCP/IP-based network.

Before DNS, the practice of mapping friendly host or computer names to IP addresses washandled via host files. Host files are easy to understand. These are static ASCII text files thatsimply map a host name to an IP address in a table-like format. Windows ships with aHOSTS file in the \winnt\system32\drivers\etc subdirectory

The fundamental problem with the host files was that these files were labor intensive. A hostfile is manually modified, and it is typically centrally administrated.

The DNS system consists of three components: DNS data (called resource records), servers(called name servers), and Internet protocols for fetching data from the servers.

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Q2. Which are the four generally accepted naming conventions?

NetBIOS Name (for instance, SPRINGERS01)

TCP/IP Address (121.133.2.44)

Host Name (Abbey)

Media Access Control (MAC)this is the network adapter hardware address

Q3. How DNS really works

DNS uses a client/server model in which the DNS server maintains a static database ofdomain names mapped to IP addresses. The DNS client, known as the resolver, performqueries against the DNS servers. The bottom line? DNS resolves domain names to IPaddress using these steps

Step 1. A client (or resolver) passes its request to its local name server. For example, theURL term www.idgbooks.com typed into Internet Explorer is passed to the DNS serveridentified in the client TCP/IP configuration. This DNS server is known as the local nameserver.

Step 2. If, as often happens, the local name server is unable to resolve the request, othername servers are queried so that the resolver may be satisfied.

Step 3. If all else fails, the request is passed to more and more, higher-level name servers

until the query resolution process starts with far-right term (for instance, com) or at the top ofthe DNS tree with root name servers

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Below is the Steps explained with the help of a chart.

Figure 8-5: How DNS works

Q4. Which are the major records in DNS?

1. Host or Address Records (A):- map the name of a machine to its numeric IP address. Inclearer terms, this record states the hostname and IP address of a certain machine. Havethree fields: Host Name, Domain, Host IP Address.

E.g.:- eric.foobarbaz.com. IN A 36.36.1.6

It is possible to map more than one IP address to a given hostname. This often happens forpeople who run a firewall and have two 19thernet cards in one machine. All you must do isadd a second A record, with every column the same save for the IP address.

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2. Aliases or Canonical Name Records (CNAME)

CNAME records simply allow a machine to be known by more than one hostname. Theremust always be an A record for the machine before aliases can be added. The host name ofa machine that is stated in an A record is called the canonical, or official name of themachine. Other records should point to the canonical name. Here is an example of aCNAME:

www.foobarbaz.com. IN CNAME eric.foobarbaz.com.

You can see the similarities to the previous record. Records always read from left to right,with the subject to be queried about on the left and the answer to the query on the right. Amachine can have an unlimited number of CNAME aliases. A new record must be enteredfor each alias.

You can add A or CNAME records for the service name pointing to the machines you wantto load balance.

3. Mail Exchange Records (MX)

MX records are far more important than they sound. They allow all mail for a domain to berouted to one host. This is exceedingly useful it abates the load on your internal hostssince they do not have to route incoming mail, and it allows your mail to be sent to anyaddress in your domain even if that particular address does not have a computer associatedwith it. For example, we have a mail server running on the fictitious machineeric.foobarbaz.com. For convenience sake, however, we want our email address to [email protected] rather than [email protected]. This is accomplished by therecord shown below:

foobarbaz.com. IN MX 10 eric.foobarbaz.com.

The column on the far left signifies the address that you want to use as an Internet emailaddress. The next two entries have been explained thoroughly in previous records. The next

column, the number 10, is different from the normal DNS record format. It is a signifier ofpriority. Often larger systems will have backup mail servers, perhaps more than one.Obviously, you will only want the backups receiving mail if something goes wrong with theprimary mail server. You can indicate this with your MX records. A lower number in an MXrecord means a higher priority, and mail will be sent to the server with the lowest number(the lowest possible being 0). If something happens so that this server becomesunreachable, the computer delivering the mail will attempt every other server listed in theDNS tables, in order of priority.

Obviously, you can have as many MX records as you would like. It is also a good idea toinclude an MX record even if you are having mail sent directly to a machine with an A record.Some sendmail programs only look for MX records.

It is also possible to include wildcards in MX records. If you have a domain where your userseach have their own machine running mail clients on them, mail could be sent directly toeach machine. Rather than clutter your DNS entry, you can add an MX record like this one:

*.foobarbaz.com. IN MX 10 eric.foobarbaz.com.

This would make any mail set to any individual workstation in the foobarbaz.com domain gothrough the server eric.foobarbaz.com.

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One should use caution with wildcards; specific records will be given precedence over onescontaining wildcards.

4. Pointer Records (PTR)

Although there are different ways to set up PTR records, we will be explaining only the mostfrequently used method, called in-addr.arpa.

In-addr.arpa PTR records are the exact inverse of A records. They allow your machine to berecognized by its IP address. Resolving a machine in this fashion is called a reverselookup. It is becoming more and more common that a machine will do a reverse lookup onyour machine before allowing you to access a service (such as a World Wide Web page).Reverse lookups are a good security measure, verifying that your machine is exactly who itclaims to be. In-addr.arpa records look as such:

6.1.36.36.in-addr.arpa. IN PTR eric.foobarbaz.com.

As you can see from the example for the A record in the beginning of this document, therecord simply has the IP address in reverse for the host name in the last column.

A note for those who run their own name servers: although Allegiance Internet is capable ofpulling zones from your name server, we cannot pull the inverse zones (these in-addr.arparecords) unless you have been assigned a full class C network. If you would like us to putPTR records in our name servers for you, you will have to fill out the online web form on thesupport.allegianceinternet.com page.

5. Name Server Records (NS)

NS records are imperative to functioning DNS entries. They are very simple; they merelystate the authoritative name servers for the given domain. There must be at least two NSrecords in every DNS entry. NS records look like this:

foobarbaz.com. IN NS draven.foobarbaz.com.There also must be an A record in your DNS for each machine you enter as A NAME serverin your domain.

If Allegiance Internet is doing primary and secondary names service, we will set up theserecords for you automatically, with nse.algx.net and nsf.algx.net as your two authoritativename servers.

6. Start Of Authority Records (SOA)

The SOA record is the most crucial record in a DNS entry. It conveys more informationthan all the other records combined. This record is called the start of authority because it

denotes the DNS entry as the official source of information for its domain. Here is anexample of a SOA record, then each part of it will be explained:

foobarbaz.com. IN SOA draven.foobarbaz.com. hostmaster.foobarbaz.com. (

1996111901 ; Serial

10800 ; Refresh

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3600 ; Retry

3600000 ; Expire

86400 ) ; Minimum

The first column contains the domain for which this record begins authority for. The next twoentries should look familiar. The draven.foobarbaz.com entry is the primary name serverfor the domain. The last entry on this row is actually an email address, if you substituted a

@ for the first .. There should always be a viable contact address in the SOA record.

The next entries are a little more unusual then what we have become used to. The serialnumber is a record of how often this DNS entry has been updated. Every time a change ismade to the entry, the serial number must be incremented. Other name servers that pullinformation for a zone from the primary only pull the zone if the serial number on the primaryname servers entry is higher than the serial number on its entry. In this way the nameservers for a domain are able to update themselves. A recommended way of using yourserial number is the YYYYMMDDNN format shown above, where the NN is the number oftimes that day the DNS has been changed.

Also, a note for Allegiance Internet customers who run their own name servers: even if theserial number is incremented, you should still fill out the web form and use the comment boxwhen you make changes asking us to pull the new zones.

All the rest of the numbers in the record are measurements of time, in seconds. Therefresh number stands for how often secondary name servers should check the primary fora change in the serial number. Retry is how long a secondary server should wait beforetrying to reconnect to primary server if the connection was refused. Expire is how long thesecondary server should use its current entry if it is unable to perform a refresh, andminimum is how long other name servers should cache, or save, this entry.

There can only be one SOA record per domain. Like NS records, Allegiance Internetsets up this record for you if you are not running your own name server.

Quick Summary of the major records in DNS

Record Type Definition

Host (A) Maps host name to IP address in a DNS zone. Has three fields:Domain, Host Name, Host IP Address.

Aliases (CNAME) Canonical name resource record that creates an alias for a hostname. CNAME records are typically used to hide implementation

details from clients. Fields include: Domain, Alias Name, For HostDNS Name.

Nameservers (NS) Identifies the DNS name servers in the DNS domain. NS recordsappear in all DNS zones and reverse zones. Fields include: Domain,Name Server DNS Name.

Pointer (PTR) Maps IP address to host name in a DNS reverse zone. Fieldsinclude: IP Address, Host DNS Name.

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Mail Exchange (MX) Specifies a mail exchange server for a DNS domain name. Note thatthe term exchange does not refer to Microsoft Exchange, aBackOffice e-mail application. However, to connect MicrosoftExchange to the Internet via the Internet Mail Server (IMS), the MXrecord must be correctly configured by your ISP.

A mail exchange server is a host that will either process or forwardmail for the DNS domain name. Processing the mail means eitherdelivering it to the addressee or passing it to a different type of mailtransport. Forwarding the mail means sending it to its final destinationserver, sending it using Simple Mail Transfer Protocol to another mailserver that is closer to the final destination, or queuing it for aspecified amount of time.

Fields include: Domain, Host Name (Optional), Mail Exchange ServerDNS Name, Preference Number.

Q5.What is a DNS zone

A zone is simply a contiguous section of the DNS namespace. Records for a zone arestored and managed together. Often, subdomains are split into several zones to makemanageability easier. For example, support.microsoft.com and msdn.microsoft.com areseparate zones, where supportand msdn are subdomains within the Microsoft.com domain.

Q6. Name the two Zones in DNS?

DNS servers can containprimaryand secondaryzones. A primary zone is a copy of a zonewhere updates can be made, while a secondary zone is a copy of a primary zone. For faulttolerance purposes and load balancing, a domain may have several DNS servers thatrespond to requests for the same information.

The entries within a zone give the DNS server the information it needs to satisfy requestsfrom other computers or DNS servers.

Q7. How many SOA record does each zone contain?

Each zone will have one SOA record. This records contains many miscellaneous settingsfor the zone, such as who is responsible for the zone, refresh interval settings, TTL (Time ToLive) settings, and a serial number (incremented with every update).

Q8. Short summary of the records in DNS.

The NS records are used to point to additional DNS servers. The PTR record is used forreverse lookups (IP to name). CNAME records are used to give a host multiple names. MXrecords are used when configuring a domain for email.

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Q9. What is an AD-integrated zone?

AD-integrated zones store the zone data in Active Directory and use the same replicationprocess used to replicate other data between domain controllers. The one catch with AD-integrated zones is that the DNS server must also be a domain controller. Overloading DNSserver responsibilities on your domain controllers may not be something you want to do if youplan on supporting a large volume of DNS requests.

Q10.What is a STUB zone?

A stub zone is a copy of a zone that contains only those resource records necessary to

identify the authoritative Domain Name System (DNS) servers for that zone. A stub zone is

used to resolve names between separate DNS namespaces. This type of resolution may be

necessary when a corporate merger requires that the DNS servers for two separate DNS

namespaces resolve names for clients in both namespaces.

The master servers for a stub zone are one or more DNS servers authoritative for the child

zone, usually the DNS server hosting the primary zone for the delegated domain name.

Q11. What does a stub zone consists of?

A stub zone consists of:

The start of authority (SOA) resource record, name server (NS) resource records, and the

glue A resource records for the delegated zone.

The IP address of one or more master servers that can be used to update the stub zone.

Q12. How the resolution in a stub zone takes place?

When a DNS client performs a recursive query operation on a DNS server hosting a stub

zone, the DNS server uses the resource records in the stub zone to resolve the query. The

DNS server sends an iterative query to the authoritative DNS servers specified in the NS

resource records of the stub zone as if it were using NS resource records in its cache. If the

DNS server cannot find the authoritative DNS servers in its stub zone, the DNS server hosting

the stub zone attempts standard recursion using its root hints.

The DNS server will store the resource records it receives from the authoritative DNS servers

listed in a stub zone in its cache, but it will not store these resource records in the stub zone

itself; only the SOA, NS, and glue A resource records returned in response to the query are

stored in the stub zone. The resource records stored in the cache are cached according to the

Time-to-Live (TTL) value in each resource record. The SOA, NS, and glue A resource records,

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which are not written to cache, expire according to the expire interval specified in the stub

zone's SOA record, which is created during the creation of the stub zone and updated during

transfers to the stub zone from the original, primary zone.

If the query was an iterative query, the DNS server returns a referral containing the servers

specified in the stub zone.

Q 13.What is the benefits of Active Directory Integration?

For networks deploying DNS to support Active Directory, directory-integrated primary zones

are strongly recommended and provide the following benefits:

* Multimaster update and enhanced security based on the capabilities of ActiveDirectory

In a standard zone storage model, DNS updates are conducted based upon a single-masterupdate model. In this model, a single authoritative DNS server for a zone is designated as the

primary source for the zone.

This server maintains the master copy of the zone in a local file. With this model, the primaryserver for the zone represents a single fixed point of failure. If this server is not available,update requests from DNS clients are not processed for the zone.

With directory-integrated storage, dynamic updates to DNS are conducted based upon amultimaster update model.

In this model, any authoritative DNS server, such as a domain controller running a DNSserver, is designated as a primary source for the zone. Because the master copy of the zone

is maintained in the Active Directory database, which is fully replicated to all domaincontrollers, the zone can be updated by the DNS servers operating at any domain controllerfor the domain.

With the multimaster update model of Active Directory, any of the primary servers for thedirectory-integrated zone can process requests from DNS clients to update the zone as longas a domain controller is available and reachable on the network.

Also, when using directory-integrated zones, you can use access control list (ACL) editing tosecure a dnsZone object container in the directory tree. This feature provides granulatedaccess to either the zone or a specified RR in the zone.

For example, an ACL for a zone RR can be restricted so that dynamic updates are onlyallowed for a specified client computer or a secure group such as a domain administratorsgroup. This security feature is not available with standard primary zones.

Note that when you change the zone type to be directory-integrated, the default for updatingthe zone changes to allow only secure updates. Also, while you may use ACLs on DNS-related Active Directory objects, ACLs may only be applied to the DNS client service.

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* Directory replication is faster and more efficient than standard DNS replication.

Because Active Directory replication processing is performed on a per-property basis, onlyrelevant changes are propagated. This allows less data to be used and submitted in updatesfor directory-stored zones.

Note: Only primary zones can be stored in the directory. A DNS server cannot storesecondary zones in the directory. It must store them in standard text files. The multimaster

replication model of Active Directory removes the need for secondary zones when all zonesare stored in Active Directory.

Q14. What is Scavenging?

DNS scavenging is the process whereby resource records are automatically removed if theyare not updated after a period of time. Typically, this applies to only resource records thatwere added via DDNS, but you can also scavenge manually added, also referred to as static,records. DNS scavenging is a recommended practice so that your DNS zones areautomatically kept clean of stale resource records.

Q15. What is the default interval when DNS server will kick off the scavenging process?

The default value is 168 hours, which is equivalent to 7 days.

DNS Q&A corner

Q1. How do I use a load balancer with my name servers?

Just wanted to ask a question about load balanced DNS servers

> via an external network load balancing appliance (i.e - F5's Big IP,> Cisco's Content Switches/ Local Directors).> The main question being the configuration whether to use 2> Master/Primary Servers or is it wiser to use 1 Primary and 1> Secondary? The reason is that I feel there are two configurations> that could be setup. One in which only the resolvers query the> virtual IP address on the load balancing appliance or actually> configure your NS records to point to the Virtual Address so that all> queries, ie - both by local queries directly from local users and> also queries from external DNS servers. I've included a text> representation of the physical configuration. Have you ever

> heard or architected such a configuration?

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> VIP = 167.147.1.5> ------------------------------------>> Load Balancer Device |> ------------------------------------> |> |> -----------------

> | |> ---------------- -------------->> DNS 1 | | DNS 2 |> ---------------- --------------> 1.1.1.1 1.1.1.2

There's usually not much need to design solutions like these, since mostname server implementations will automatically choose the name serverthat responds most quickly. In other words, if DNS 1 fails, remotename servers will automatically try DNS 2, and vice versa.

However, it can be useful for resolvers. In that case, you don't need toworry about NS records (since resolvers don't use them), just setting upa virtual IP address.

> Also, Is there any problems in running two Master/Primaries?

Just that you'd have to synchronize the zone data between the twomanually.

Q2. How does reverse mapping work?

How can reverse lookup possibly work on the Internet - how can a local> resolver or ISP's Dns server find the pointer records please? E.g. I run> nslookup 161.114.1.206 & get a reply for a Compaq server> - how does it know where to look? Is there a giant reverse lookup zone in> the sky?

Yes, actually, there is: in-addr.arpa.

If a resolver needs to reverse map, say, 161.114.1.206 to a domain name, it first invertsthe octets of the IP address and appends "in-addr.arpa." So, in this case, the IP

address would become the domain name 206.1.114.161.in-addr.arpa.

Then the resolver sends a query for PTR records attached to that domain name. Ifnecessary, the resolution process starts at the root name servers. The root nameservers refer the querier to the 161.in-addr.arpa name servers, run by an organizationcalled ARIN, the American Registry for Internet Numbers. These name servers refer thequerier to 1.114.161.in-addr.arpa name servers, run by Compaq. And, finally, thesename servers map the IP address to inmail.compaq.com.

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Q3. What are the pros and cons of running slaves versus caching-only name servers?

> Question: I am in the process of setting up dns servers in several locations for my> business. I have looked into having a primary master server running in my server> room and adding slave servers in the other areas. I then thought I could just> setup a primary and a single slave server and run caching only servers in the other> areas. What are the pros and cons of these two options, or should I run a slave> server in every location and still have a caching server with it? I just don't

> know what the best way would be. Please help.

The main advantage of having slaves everywhere is that you have asource of your own zone data on each name server. So if you havea community of hosts near each slave that look up domain names inyour zones, the local name server can answer most of their queries.

On the other hand, administering slaves is a little more work thanadministering caching-only name servers, and a little greater burdenon the primary master name server.

Q4. Can I set a TTL on a specific record?

> Is it possible to setup ttl values for individual records in bind?

Sure. You specify explicit TTLs in a record's TTL field, between the ownerfield and the class field:

foo.example. 300 IN A 10.0.0.1

Q5. Can I use an A record instead of an MX record?

> I have a single machine running DNS mail and web for a domain> and I'm not sure that I have DNS setup properly. If the machine> that is running the mail is the name of the domain does there need> to be an MX record for mail?

Technically, no. Nearly all mailers will look up A records for adomain name in a mail destination if no MX records exist.

> If an MX record is not needed, how would you put in an MX> record for a backup mailserver.

You can't. If you want to use a backup mailer, you need to useMX records.

> www cname 192.168.0.1> mail cname 192.168.0.1> pop cname 192.168.0.1> smtp cname 192.168.0.1

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These CNAME records are all incorrect. CNAME records createan alias from one domain name to another, so the field after "CNAME"must contain a domain name, not an IP address. For example:www CNAME foo.example.

Q6. What are a zone's NS records used for?

> Could you elaborate a little bit on why do we need to put NS records for

> the zone we are authoritative for ?> The parent name server handles these already. Is there any problem if our> own NS records have lower TTLs than the records from parent name server ?

That's a good question. The NS records from your zone data file are used for several things:

- Your name servers returns them in responses to queries, in the authority section of the DNSmessage. Moreover, the set of NS records that comes directly from your name serversupersedes the set that a querier gets from your parent zone's name servers, so if the twosets are different, yours "wins."

- Your name servers use the NS records to determine where to send NOTIFY messages.

- Dynamic updaters determine where to send updates using the NS records, which they oftenget from the authoritative name servers.

Q7. Do slaves only communicate with their masters over TCP?

> When the slave zone checks in with the master zone for the serial number, is> all this traffic happening on TCP. For example, if you have acl's blocking> udp traffic but allowing tcp traffic will the transfer work or will it fail> due to the slaves inability to query for the SOA record on udp?

No. The refresh query (for the zone's SOA record) is usually done over UDP.

Q8. What's the largest number I can use in an MX record?

> Could you tell us the highest possible number we can use for the MX> preference ?

Preference is an unsigned, 16-bit number, so the largest number youcan use is 65535.

Q9. Why are there only 13 root name servers?

> I'm very wondering why there are only 13 root servers on globally.> Some documents explain that one of the reason is technical limit on Domain> Name System (without any detailed explanation).> From my understanding, it seems that some limitation of NS record numbers> in DNS packet that specified by certain RFCs, or just Internet policy stuff.>> Which one is proper reason?

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It's a technical limitation. UDP-based DNS messages can be up to 512 byteslong, and only 13 NS records and their corresponding A records will fit into a DNS messagethat size.

IMP informationhttp://www.menandmice.com/online_docs_and_faq/glossary/glossarytoc.htm

Q1.Which is the FIVE FSMO roles?

Schema Master Forest Level One per forest

Domain Naming Master Forest Level One per forest

PDC Emulator Domain Level One per domain

RID Master Domain Level One per domain

Infrastructure Master Domain Level One per domain

Q2. What are their functions?

1. Schema Master(Forest level)

The schema master FSMO role holder is the Domain Controller responsible forperforming updates to the active directory schema. It contains the only writable copyof the AD schema. This DC is the only one that can process updates to the directoryschema, and once the schema update is complete, it is replicated from the schemamaster to all other DCs in the forest. There is only one schema master in the forest.

2. Domain Naming Master(Forest level)

The domain naming master FSMO role holder is the DC responsible for makingchanges to the forest-wide domain name space of the directory. This DC is the onlyone that can add or remove a domain from the directory, and that is it's majorpurpose. It can also add or remove cross references to domains in externaldirectories. There is only one domain naming master in the active directory or forest.

3. PDC Emulator(Domain level)

In a Windows 2000 domain, the PDC emulator server role performs the followingfunctions:Password changes performed by other DCs in the domain are replicated

preferentially to the PDC emulator first.Authentication failures that occur at a given DC in a domain because of an incorrectpassword are forwarded to the PDC emulator for validation before a bad passwordfailure message is reported to the user.Account lockout is processed on the PDC emulator.Time synchronization for the domain.

Group Policy changes are preferentially written to the PDC emulator.

Additionally, if your domain is a mixed mode domain that contains Windows NT 4BDCs, then the Windows 2000 domain controller, that is the PDC emulator, acts as aWindows NT 4 PDC to the BDCs.

There is only one PDC emulator per domain.

Note: Some consider the PDC emulator to only be relevant in a mixed mode domain.This is not true. Even after you have changed your domain to native mode (no more

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NT 4 domain controllers), the PDC emulator is still necessary for the reasons above.

4. RID Master(Domain level)

The RID master FSMO role holder is the single DC responsible for processing RIDPool requests from all DCs within a given domain. It is also responsible for removingan object from its domain and putting it in another domain during an object move.

When a DC creates a security principal object such as a user, group or computer

account, it attaches a unique Security ID (SID) to the object. This SID consists of adomain SID (the same for all SIDs created in a domain), and a relative ID (RID) thatmakes the object unique in a domain.

Each Windows 2000 DC in a domain is allocated a pool of RIDs that it assigns to thesecurity principals it creates. When a DC's allocated RID pool falls below a threshold,that DC issues a request for additional RIDs to the domain's RID master. The domainRID master responds to the request by retrieving RIDs from the domain's unallocatedRID pool and assigns them to the pool of the requesting DC.

There is one RID master per domain in a directory.

5. Infrastructure Master(Domain level)

The DC that holds the Infrastructure Master FSMO role is responsible for crossdomain updates and lookups. When an object in one domain is referenced byanother object in another domain, it represents the reference by the GUID, the SID(for references to security principals), and the distinguished name (DN) of the objectbeing referenced. The Infrastructure role holder is the DC responsible for updating anobject's SID and distinguished name in a cross-domain object reference.

When a user in DomainA is added to a group in DomainB, then the Infrastructuremaster is involved. Likewise, if that user in DomainA, who has been added to agroup in DomainB, then changes his username in DomainA, the Infrastructure mastermust update the group membership(s) in DomainB with the name change.

There is only one Infrastructure master per domain.

Q3. What if a FSMO server fails?

Schema Master No updates to the Active Directory schema will be possible.Since schema updates are rare (usually done by certain

applications and possibly an Administrator adding an attribute toan object), then the malfunction of the server holding the SchemaMaster role will not pose a critical problem.

Domain Naming Master The Domain Naming Master must be available when adding orremoving a domain from the forest (i.e. running DCPROMO). If itis not, then the domain cannot be added or removed. It is alsoneeded when promoting or demoting a server to/from a DomainController. Like the Schema Master, this functionality is onlyused on occasion and is not critical unless you are modifying

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The Schema Master and Domain Naming Master should reside on the same server, and thatmachine should be a Global Catalog server. Since all three are, by default, on the firstdomain controller installed in a forest, then you can leave them as they are.Note: According to MS, the Domain Naming master needs to be on a Global Catalog Server.If you are going to separate the Domain Naming master and Schema master, just make surethey are both on Global Catalog servers.

IMP:- Why Infrastructure Master should not be on the same server that acts as a GlobalCatalog server?The Infrastructure Master should not be on the same server that acts as a Global Catalog

server.The reason for this is the Global Catalog contains information about every object in the forest.When the Infrastructure Master, which is responsible for updating Active Directory informationabout cross domain object changes, needs information about objects not in it's domain, itcontacts the Global Catalog server for this information. If they both reside on the same server,then the Infrastructure Master will never think there are changes to objects that reside in otherdomains because the Global Catalog will keep it constantly updated. This would result in theInfrastructure Master never replicating changes to other domain controllers in its domain.

Note: In a single domain environment this is not an issue.

Microsoft also recommends that the PDC Emulator and RID Master be on the same server.This is not mandatory like the Infrastructure Master and the Global Catalog server above, butis recommended. Also, since the PDC Emulator will receive more traffic than any other FSMOrole holder, it should be on a server that can handle the load.

It is also recommended that all FSMO role holders be direct replication partners and theyhave high bandwidth connections to one another as well as a Global Catalog server.

Q7.What permissions you should have in order to transfer a FSMO role?

Before you can transfer a role, you must have the appropriate permissions depending onwhich role you plan to transfer:

Schema Master member of the Schema Admins group

Domain Naming Master member of the Enterprise Admins group

PDC Emulatormember of the Domain Admins group and/orthe Enterprise Admins group

RID Mastermember of the Domain Admins group and/or

the Enterprise Admins group

Infrastructure Mastermember of the Domain Admins group and/orthe Enterprise Admins group

FSMO TOOLS

Q8. Tools to find out what servers in your domain/forest hold what server roles?

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1. Active Directory Users and Computers:- use this snap-in to find out where thedomain level FSMO roles are located (PDC Emulator, RID Master, Infrastructure Master), andalso to change the location of one or more of these 3 FSMO roles.

Open Active Directory Users and Computers, right click on the domain you want to view theFSMO roles for and click "Operations Masters". A dialog box (below) will open with three tabs,one for each FSMO role. Click each tab to see what server that role resides on. To changethe server roles, you must first connect to the domain controller you want to move it to. Do

this by right clicking "Active Directory Users and Computers" at the top of the Active DirectoryUsers and Computers snap-in and choose "Connect to Domain Controller". Once connectedto the DC, go back into the Operations Masters dialog box, choose a role to move and clickthe Change button.When you do connect to another DC, you will notice the name of that DC will be in the fieldbelow the Change button (not in this graphic).

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2. Active Directory Domains and Trusts - use this snap-in to find out where theDomain Naming Master FSMO role is and to change it's location.

The process is the same as it is when viewing and changing the Domain level FSMOroles in Active Directory Users and Computers, except you use the Active DirectoryDomains and Trusts snap-in. Open Active Directory Domains and Trusts, right click"Active Directory Domains and Trusts" at the top of the tree, and choose "OperationsMaster". When you do, you will see the dialog box below. Changing the server that

houses the Domain Naming Master requires that you first connect to the new domaincontroller, then click the Change button. You can connect to another domaincontroller by right clicking "Active Directory Domains and Trusts" at the top of the

Active Directory Domains and Trusts snap-in and choosing "Connect to DomainController".

3. Active Directory Schema - this snap-in is used to view and change the SchemaMaster FSMO role. However... the Active Directory Schema snap-in is not part of thedefault Windows 2000 administrative tools or installation. You first have to install theSupport Tools from the \Support directory on the Windows 2000 server CD or installthe Windows 2000 Server Resource Kit. Once you install the support tools you canopen up a blank Microsoft Management Console (start, run, mmc) and add the snap-in to the console. Once the snap-in is open, right click "Active Directory Schema" atthe top of the tree and choose "Operations Masters". You will see the dialog boxbelow. Changing the server the Schema Master resides on requires you first connectto another domain controller, and then click the Change button.

You can connect to another domain controller by right clicking "Active DirectorySchema" at the top of the Active Directory Schema snap-in and choosing "Connect toDomain Controller

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4.Netdom

The easiest and fastest way to find out what server holds what FSMO role is by usingthe Netdom command line utility. Like the Active Directory Schema snap-in, theNetdom utility is only available if you have installed the Support Tools from theWindows 2000 CD or the Win2K Server Resource Kit.

To use Netdom to view the FSMO role holders, open a command prompt window andtype:netdom query fsmo and press enter. You will see a list of the FSMO role servers:

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5. Active Directory Relication Monitoranother tool that comes with the SupportTools is the Active Directory Relication Monitor. Open this utility from Start,Programs, Windows 2000 Support Tools. Once open, click Edit, Add MonitoredServer and add the name of a Domain Controller. Once added, right click the Servername and choose properties. Click the FSMO Roles tab to view the servers holding

the 5 FSMO roles (below). You cannot change roles using Replication Monitor, butthis tool has many other useful purposes in regard to Active Directory information. It issomething you should check out if you haven't already.

Finally, you can use the Ntdsutil.exe utility to gather information about and changeservers for FSMO roles. Ntdsutil.exe, a command line utility that is installed withWindows 2000 server, is rather complicated and beyond the scope of this document.

6. DUMPFSMOS

Command-line tool to query for the current FSMO role holders

Part of the Microsoft Windows 2000 Server Resource Kit

Downloadable from http://www.microsoft.com/windows2000

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/techinfo/reskit/default.asp

Prints to the screen, the current FSMO holders

Calls NTDSUTIL to get this information

7. NLTEST

Command-line tool to perform common network administrative tasks

Type nltest /? for syntax and switches

Common uses

Get a list of all DCs in the domain

Get the name of the PDC emulator

Query or reset the secure channel for a server

Call DsGetDCName to query for an available domain controller

8. Adcheck (470k) (3rd

party)

A simple utility to view information about AD and FSMO roles

http://www.svrops.com/svrops/downloads/zipfiles/ADcheck.msi

Q9. How to Transfer and Seize a FSMO Role

http://support.microsoft.com/default.aspx?scid=kb;en-us;Q255504

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GROUP POLICY

Q1. What are Group Policies?

Group Policies are settings that can be applied to Windows computers, users or both. InWindows 2000 there are hundreds of Group Policy settings. Group Policies are usually usedto lock down some aspect of a PC. Whether you don't want users to run Windows Update or

change their Display Settings, or you want to insure certain applications are installed oncomputers - all this can be done with Group Policies.

Group Policies can be configured eitherLocally or by Domain Polices. Local policies can beaccessed by clicking Start, Run and typing gpedit.msc. They can also be accessed byopening the Microsoft Management Console (Start, Run type mmc), and adding the GroupPolicy snap-in. You must be an Administrator to configure/modify Group Policies. Windows2000 Group Policies can only be used on Windows 2000 computers or Windows XPcomputers. They cannot be used on Win9x or WinNT computers.

Q2. Domain policy gets applied to whom ?

Domain Policies are applied to computers and users who are members of a Domain, andthese policies are configured on Domain Controllers. You can access Domain GroupPolices by opening Active Directory Sites and Services (these policies apply to the Site levelonly) or Active Directory Users and Computers (these policies apply to the Domain and/orOrganizational Units).

Q3. From Where to create a Group Policy?

To create a Domain Group Policy Object open Active Directory Sites and Services and rightclick Default-First-Site-Name or another Site name, choose properties, then the Group Policy

tab, then click the New button. Give the the GPO a name, then click the Edit button toconfigure the policies.For Active Directory Users and Computers, it the same process except you right click theDomain or an OU and choose properties.

Q4. Who can Create/Modify Group Policies?

You have to have Administrative privileges to create/modify group policies. The followingtable shows who can create/modify group policies:

Policy Type Allowable Groups/Users

Site Level Group Policies Enterprise Administrators and/or Domain Administrators inthe root domain. The root domain is the first domain createdin a tree or forest. The Enterprise Administrators group isfound only in the root domain.

Domain Level GroupPolicies

Enterprise Administrators, Domain Administrators ormembers of the built-in group - Group Policy CreatorOwners. By default only the Administrator user account is a

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member of this group

OU Level Group Policies Enterprise Administrators, Domain Administrators ormembers of the Group Policy Creator Owners. By defaultonly the Administrator user account is a member of thisgroup.

Additionally, at the OU level, users can be delegated control

for the OU Group Policies by starting the Delegate ControlWizard (right click the OU and choose Delegate Control).However, the wizard only allows the delegated user to Linkalready created group policies to the OU. If you want togive the OU administrators control over creating/modifyinggroup policies, add them to the Group Policy CreatorOwners group for the domain.

Local Group Policies The local Administrator user account or members of thelocal Administrators group.

Q5. How are Group Policies Applied?

Group Polices can be configured locally, at the Site level, the Domain level or at theOrganizational Unit (OU) level. Group Policies are applied in a Specific Order, LSDO - Localpolicies first, then Site based policies, then Domain level policies, then OU polices, thennested OU polices (OUs within OUs). Group polices cannot be linked to a specific user orgroup, only container objects.

In order to apply Group Polices to specific users or computers, you add users (or groups) andcomputers to container objects. Anything in the container object will then get the policies

linked to that container. Sites, Domains and OUs are considered container objects.

Computer and User Active Directory objects do not have to put in the same container object.For example, Sally the user is an object in Active Directory. Sally's Windows 2000 Pro PC isalso an object in Active Directory. Sally the user object can be in one OU, while her computerobject can be another OU. It all depends on how you organize your Active Directory structureand what Group Policies you want applied to what objects.

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User and Computer Policies

There are two nodes in each Group Policy Object that is created. A Computernode and a

UserNode. They are called Computer Configuration and User Configuration (see imageabove). The polices configured in the Computer node apply to the computer as a whole.Whoever logs onto that computer will see those policies.Note: Computer policies are also referred to as machine policies.

User policies are user specific. They only apply to the user that is logged on. When creatingDomain Group Polices you can disable either the Computer node or User node of the GroupPolicy Object you are creating. By disabling a node that no policies are defined for, you aredecreasing the time it takes to apply the polices.To disable the node polices: After creating a Group Policy Object, click that Group PolicyObject on the Group Policy tab, then click the Properties button. You will see two check boxes

at the bottom of the General tab.

It's important to understand that when Group Policies are being applied, all the policies for anode are evaluated first, and then applied. They are not applied one after the other. Forexample, say Sally the user is a member of the Development OU, and the Security OU. WhenSally logs onto her PC the policies set in the User node of the both the Development OU andthe Security OU Group Policy Objects are evaluated, as a whole, and then applied to Sally theuser. They are not applied Development OU first, and then Security OU (or visa- versa).The same goes for Computer policies. When a computer boots up, all the Computer nodepolices for that computer are evaluated, then applied.

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When computers boot up, the Computer policies are applied. When users login, the Userpolicies are applied. When user and computer group policies overlap, the computer policywins.

Note: IPSec and EFS policies are not additive. The last policy applied is the policy theuser/computer will have.

When applying multiple Group Policies Objects from any container, Group Policies are appliedfrom bottom to top in the Group Policy Object list. The top Group Policy in the list is the last tobe applied. In the above image you can see three Group Policy Objects associated with theHuman Resources OU. These polices would be applied No Windows Update first, then NoDisplay Settings, then No ScreenSaver. If there were any conflicts in the policy settings, theone above it would take precedence.

Q6.How to disable Group Policy Objects

When you are creating a Group Policy Object, the changes happen immediately. There is no"saving" of GPOs. To prevent a partial GPO from being applied, disable the GPO while youare configuring it. To do this, click the Group Policy Object on the Group Policy tab and underthe Disable column, double click - a little check will appear. Click the Edit button, make yourchanges, then double click under the Disable column to re-enable the GPO. Also, if you wantto temporarily disable a GPO for troubleshooting reasons, this is the place to do it. You canalso click the Options button on the Group Policy tab and select the Disabled check box.

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Q7. When does the group policy Scripts run?

Startup scripts are processed at computer bootup and before the user logs in.Shutdown scripts are processed after a user logs off, b

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