Advanced Communication Networks Lab - 05 Iqbal Uddin Khan

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Lab – 05

DNS Q1. Run nslookup to obtain the IP address of a Web server in Asia.

Ans: I ran nslookup www.hamdard.edu.pk. Below is the screen shot.

Q2. Run nslookup to determine the authoritative DNS servers for a university in Europe.

Ans: I ran nslookup http://www.qub.ac.uk. The Queens University of Belfast, below is the screen shot.

Q3. Run nslookup so that one of the DNS servers obtained in Question 2 is queried for the mail servers for

Yahoo! mail.

Ans: Below is the screenshot what I observed.

Q4. Locate the DNS query and response messages. Are they sent over UDP or TCP?

Ans: The DNS packets were sent over UDP. Screen shot is on next page.

Advanced Communication Networks Lab - 05 Iqbal Uddin Khan

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Q5. What is the destination port for the DNS query message? What is the source port of DNS response

message?

Ans: The both destination and query port were 53. Can be view on above and below pasted screenshots.

Q6. To what IP address is the DNS query message sent? Use ipconfig to determine the IP address of your local

DNS server. Are these two IP addresses the same?

Ans: It was sent to 192.168.1.1, can be observed in above pasted screenshots, yes it is the same and can be

observed in below pasted screenshot.

Q7. Examine the DNS query message. What “Type” of DNS query is it? Does the query message contain any

“answers”?

Ans: It is a type A query and do not contains any answer, the screenshot is on next page

Advanced Communication Networks Lab - 05 Iqbal Uddin Khan

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Q8. Examine the DNS response message. How many “answers” are provided? What does each of these

answers contain?

Ans: Only one packet of response received having Answer contains ip address “64.170.98.30”.

Q9. Consider the subsequent TCP SYN packet sent by your host. Does the destination IP address of the SYN

packet correspond to any of the IP addresses provided in the DNS response message?

Ans: Yes! It corresponds to 64.170.98.30, screenshot is below.

Q10. This web page contains images. Before retrieving each image, does your host issue new DNS queries?

Ans: Yes! It issues different DNS queries for embedded links like www.rfc-editor.org, datatracker.ietf.org, and

wiki.tools.ietf.org. Screenshot is on next page.

Advanced Communication Networks Lab - 05 Iqbal Uddin Khan

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With nslookup –www.mit.edu

Q11. What is the destination port for the DNS query message? What is the source port of DNS response

message?

Ans: Source is 192.168.0.105 and Destination is 192.168.1.1, shown in screenshot below.

Q12. To what IP address is the DNS query message sent? Is this the IP address of your default local DNS

server?

Ans: It was sent to 192.168.1.1 and my local DNS address is also 192.168.1.1

Q13. Examine the DNS query message. What “Type” of DNS query is it? Does the query message contain any

“answers”?

Ans: The query is type A and do not contain any answer. Packet’s screenshot is on next page.

Advanced Communication Networks Lab - 05 Iqbal Uddin Khan

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Q14. Examine the DNS response message. How many “answers” are provided? What does each of these

answers contain?

Ans: It contains a single answer ,including ip address and web address.

Q15. Provide a screenshot.

Ans: It is on next page.

Advanced Communication Networks Lab - 05 Iqbal Uddin Khan

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Repeating with nslookup –type=NS mit.edu

Q16. To what IP address is the DNS query message sent? Is this the IP address of your default local DNS

server?

Ans: It is sent to 192.168.1.1 and my local is same, as shown in Q12.

Advanced Communication Networks Lab - 05 Iqbal Uddin Khan

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Q17. Examine the DNS query message. What “Type” of DNS query is it? Does the query message contain any

“answers”?

Ans: The query is type A and do not contain any answer. As same as Q13.

Q18. Examine the DNS response message. What MIT name servers does the response message provide? Does

this response message also provide the IP addresses of the MIT name servers?

Ans: It contains - mit.edu: type NS, class IN, ns W20NS.mit.edu

mit.edu: type NS, class IN, ns STRAWB.mit.edu

mit.edu: type NS, class IN, ns BITSY.mit.edu

but I cannot find ip addresses. Screenshot is below.

Advanced Communication Networks Lab - 05 Iqbal Uddin Khan

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Q19. Provide a screenshot

Repeating with nslookup www.aiit.or.kr bitsy.mit.edu

Q20. To what IP address is the DNS query message sent? Is this the IP address of your default local DNS

server? If not, what does the IP address correspond to?

Ans: It was sent to 18.72.0.3, it is not my local DNS and it corresponds to bitsy.mit.edu. See screenshot.

Q21. Examine the DNS query message. What “Type” of DNS query is it? Does the query message contain any

“answers”?

Ans: It is the Type PTR query and don’t contain any answer. Screen shot is on next page.

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Q22. Examine the DNS response message. How many “answers” are provided? What does each of these

answers contain?

Ans: It contains one answer along with the additional records as asked in Q18. Screen shot to be observed

below.

Q23. Provide a screenshot.