Name: Đỗ Minh Bảo Huy
ID: N22DCCN133
DNS
1. nslookup
1. Run nslookup to obtain the IP address of the web server for the Indian Institute
of Technology in Bombay, India: www.iitb.ac.in. What is the IP address of
www.iitb.ac.in
- IP address of www.iitb.ac.in: 103.21.124.133
2. What is the IP address of the DNS server that provided the answer to your
nslookup command in question 1 above?
- IP address of the DNS server: 2402:800:20ff:6666::1
3. Did the answer to your nslookup command in question 1 above come from an
authoritative or non-authoritative server?
- Non-authoritative
4. Use the nslookup command to determine the name of the authoritative name
server for the iit.ac.in domain. What is that name? (If there are more than one
authoritative servers, what is the name of the first authoritative server returned by
nslookup)? If you had to find the IP address of that authoritative name server, how
would you do so?
2. The DNS cache on your computer
3. Tracing DNS with Wireshark
5. Locate the first DNS query message resolving the name gaia.cs.umass.edu. What
is the packet number6 in the trace for the DNS query message? Is this query
message sent over UDP or TCP?
- NO:15 UDP
6. Now locate the corresponding DNS response to the initial DNS query. What is
the packet number in the trace for the DNS response message? Is this response
message received via UDP or TCP?
- No:17 UDP
7. What is the destination port for the DNS query message? What is the source port
of the DNS response message?
-
8. To what IP address is the DNS query message sent?
-
9. Examine the DNS query message. How many “questions” does this DNS
message contain? How many “answers” answers does it contain?
- 1 question, 0 answer
10. Examine the DNS response message to the initial query message. How many
“questions” does this DNS message contain? How many “answers” answers does it
contain?
- 1 question, 1 answer
11. The web page for the base file http://gaia.cs.umass.edu/kurose_ross/ references
the image object
http://gaia.cs.umass.edu/kurose_ross/header_graphic_book_8E_2.jpg , which, like
the base webpage, is on gaia.cs.umass.edu. What is the packet number in the trace
for the initial HTTP GET request for the base file
http://gaia.cs.umass.edu/kurose_ross/? What is the packet number in the trace of
the DNS query made to resolve gaia.cs.umass.edu so that this initial HTTP request
can be sent to the gaia.cs.umass.edu IP address? What is the packet number in the
trace of the received DNS response? What is the packet number in the trace for the
HTTP GET request for the image object
http://gaia.cs.umass.edu/kurose_ross/header_graphic_book_8E2.jpg? What is the
packet number in the DNS query made to resolve gaia.cs.umass.edu so that this
second HTTP request can be sent to the gaia.cs.umass.edu IP address? Discuss how
DNS caching affects the answer to this last question.
12. What is the destination port for the DNS query message? What is the source
port of the DNS response message?
- 53
13. To what IP address is the DNS query message sent? Is this the IP address of
your default local DNS server?
- 192.168.1.7 it’s my local DNS
14. Examine the DNS query message. What “Type” of DNS query is it? Does the
query message contain any “answers”?
- Type:A it doesn’t contain any aswers
15. Examine the DNS response message to the query message. How many
“questions” does this DNS response message contain? How many “answers”?
- 1 question, 1 answer
16. To what IP address is the DNS query message sent? Is this the IP address of
your default local DNS server?
- My DNS server: 192.168.1.7
17. Examine the DNS query message. How many questions does the query have?
Does the query message contain any “answers”?
- 1 question, 0 answer
18. Examine the DNS response message (in particular the DNS response message
that has type “NS”). How many answers does the response have? What
information is contained in the answers? How many additional resource records are
returned? What additional information is included in these additional resource
records (if additional information is returned)?
