lab assignment at last

8/8/2019 Lab Assignment at Last

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Ans# 1

To obtain IP address of a Web server in Asia by Running nslookup

Ans#2.

To determine the authoritative DNS servers for a university in Europe bynslookup.

www.ox.ac.uk

dns0.ox.ac.uk

dns1.ox.ac.uk

dns2.ox.ac.uk

ns2.ja.net

http://www.ox.ac.uk/

http://www.ox.ac.uk/



Ans 6: DNS server address is 172.16.64.61. Both are the same.

Ans 7: Examine the DNS query message. What “Type” of DNS query is it? Doesthe query message contain any “answers”?

ANS

DNS Query is of “type A”. No “answers” contained in the message.

8. Examine the DNS response message. How many “answers” are provided?

What does each of these answers contain?

ANS

Only one answer is provided. Each answer contain

• Name

• Type

• Class

• Time to live

• Data length

• Address

9. Consider the subsequent TCP SYN packet sent by your host. Does thedestination IP address of the SYN packet correspond to any of the IP addressesprovided in the DNS response message?

ANSYes the IP address of the destination is the same 172.16.64.61



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

ANSNo additional DNS queries were found.

11. What is the destination port for the DNS query message? What is the sourceport of DNS response message?

Ans

Destination port for the DNS query message is 58036

Source port of DNS response message is 53.

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

Ans

IP address to which the DNS query message was sent is 172.16.13.99. It

is the same local DNS server

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

Ans:

It is a type A query. It has no answers.

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

ANS

Only one answer is provided. Each answer contain

• Name

• Type

• Class

• Time to live

• Data length

• Address



15

Screenshot

16: To what IP address is the DNS query message sent? Is this the IP address of

your default local DNS server?

IP address to which the DNS query message was sent is 172.16.13.99. It is thesame local DNS server.

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

DNS Query is of “type NS (authoritative name server)”. No “answers” containedin the message.



Ans: to 18 and 19.

20

The ip of the DNS querry is 172.16.64.61

21

DNS Query is of “type A (host address)”. No “answers” contained in themessage.



Ans: to Question no.22

lab assignment at last

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