Princess Nora Bint Abdulrahman UniversityFaculty of Computer and Information SciencesDepartment of Networks and Telecommunications

NET431D-Advanced network servicesSummer Semester 1436/1437 HAssignment 1

HW Answers 1

Q1. Which version of IP is the most prevalent today?

IPv4

Q2. Does all traffic running on the internet use TCP?

No, other transport layer protocols, such as UDP, are also used. Some traffic uses no transport protocol, such as ICMP.

Q3. Compare the address space between IPv4 and IPv6. How many bits are used in each?

IPv4 - 32 bits; IPv6 - 128 bits

Q4. Why is UDP needed ?Why can’t a user program directly access IP ?

UDP provides the source and destination port addresses and a checksum that covers the data field. These functions would not normally be performed by protocols above the transport layer. Thus UDP provides a useful, though limited, service.

Q5. IP, TCP, and UDP all discard a packet that arrives with a checksum error and do not attempt to notify the source. Why?

In the case of IP and UDP, these are unreliable protocols that do not guarantee delivery, so they do not notify the source. TCP does guarantee delivery. However, the technique that is used is a timeout. If the source does not receive an acknowledgment to data within a given period of time, the source retransmits.

Q6. Why does the TCP header have a header length field while the UDP header does not?

UDP has a fixed-sized header. The header in TCP is of variable length.