2011
Vietnamese-German
University
Nguyen Dinh Thong
[COMPUTER NETWORKING]
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Exercises
Chapter 01
Chapter 02
Problem 1:
Beside GET and POST, there are some other methods in HTTP/1.0 and HTTP 1.1 such as
HEAD: asks server to leave requested object out of response.
PUT: uploads file in entity body to path specified in URL field.
DELETE: deletes file specified in URL field.
Problem 2:
-Total amount of time to obtain the IP address is:
RTT1+ RTT2+…+ RTTn
-The object/file transmission time is
2RTT + Transmission time
-Since RTT0 = RTT, and Transmission time of the object is assumed zero. Therefore, the time
elapses from when the client clicks on the link until the client receives the object is:
2RTT0 + RTT1+RTT2+…+RTTn
Problem 3:
Problem 4:
- The well known port numbers for
o FTP: 21
o TFTP: 69
o NTP: 123
- Second source for list of TCP and UDP port numbers :
http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers
Problem 5:
Problem 6:
-It is possible.
- Mail server: mail.hostname. Example hostname: foo.com -> mail server can be ‘mail.foo.com’.
Wireshark Labs
Wireshark HTTP
1. The Basic HTTP GET/response interaction
1. Is your browser running HTTP version 1.0 or 1.1? What version of HTTP is the server running?
Answer:
- My browser verion: HTTP 1.1
-Version of HTTP the server running:
2. What languages (if any) does your browser indicate that it can accept to the server?
Answer:
Accept-Language: vi-vn,vi;q=0.8,en-us;q=0.5,en;q=0.3\r\n
=> Vietnamese and English are both accepted by the server.
3. What is the IP address of your computer? Of the gaia.cs.umass.edu server?
Answer:
-IP address of my computer: 192.168.1.177
-IP address of the gaia.cs.umass.edu server: 128.119.245.12
4. What is the status code returned from the server to your browser?
Answer:
- Status code: 304 – Not modified.
5. When was the HTML file that you are retrieving last modified at the server?
6. How many bytes of content are being returned to your browser?
7. By inspecting the raw data in the packet content window, do you see any headers within the data
that are not displayed in the packet-listing window? If so, name one.
2. The HTTP CONDITIONAL GET/response interaction
8. Inspect the contents of the first HTTP GET request from your browser to the server. Do you see an IFMODIFIED-SINCE” line in the HTTP GET?
9. Inspect the contents of the server response. Did the server explicitly return the contents of the file?
How can you tell?
10. Now inspect the contents of the second HTTP GET request from your browser to the server. Do you
see an “IF-MODIFIED-SINCE:” line in the HTTP GET? If so, what information follows the “IF-MODIFIEDSINCE:” header?
11. What is the HTTP status code and phrase returned from the server in response to this second HTTP
GET? Did the server explicitly return the contents of the file? Explain.
3. Retrieving Long Documents
12. How many HTTP GET request messages were sent by your browser?
13. How many data-containing TCP segments were needed to carry the single HTTP response?
14. What is the status code and phrase associated with the response to the HTTP GET request?
15. Are there any HTTP status lines in the transmitted data associated with a TCP-induced
Continuation”?
4. HTML Documents with Embedded Objects
16. How many HTTP GET request messages were sent by your browser? To which Internet addresses
were these GET requests sent?
17. Can you tell whether your browser downloaded the two images serially, or whether they were
downloaded from the two web sites in parallel? Explain.
5 HTTP Authentication
18. What is the server’s response (status code and phrase) in response to the initial HTTP GET message
from your browser?
19. When your browser’s sends the HTTP GET message for the second time, what new field is included in
the HTTP GET message?
Wireshark DNS
Wireshark UDP
Wireshark TCP
Wireshark IP
Wireshark ICMP
Wireshark DHCP
Wireshark EthernetARP