Homework 8 (Due 11/30) (100)
Note: Typed homework solutions are preferred.
Problem 1 (10)
Read the article "Operation of a root DNS server" written by A. Kato
and J. Murai, published on IEICE Trans. Commun. Vol.E84-B, No.8
August 2001. Answer the following questions:
- How many root servers are currently functioning in the world?
- What are their location? (country and city)
- What are their hostname and ip address?
Problem 2 (10)
Use "dig" command to find out the RR of aicip.ece.utk.edu. List the
output and answer the following questions:
- What is/are the authoritative DNS server(s) of aicip?
- What is the TTL value of the record?
Use dig command to find out the RR of one of the root DNS server (any of the
13 would be fine). List the output and answer the following questions:
- What is/are the authoritative DNS server(s) of that root DNS
server?
- What is the TTL value of the record?
Problem 3 (20)
Draw a table to summarize the difference between the four application
protocols: DNS, SMTP, HTTP, and FTP. You can compare them from the
following aspects: transport layer service, stateless/state,
pull/push, port no, non-persistent/persistent, RFC no., etc.
Problem 4 (short answer questions) (30)
- (8) Explain how DNS server helps achieve load
balancing (load distribution)
- (10) What is the mail transfer
protocol used in the Internet? What are the possible mail access
protocols used between the receiver's mail server and the user agent?
Give one application example (software) for each mail access protocol.
What are the protocols used between the sender's mail server and the
sender? Also give one application example for each protocol.
- (6) Explain the difference between pull protocol and push protocol.
- (6) Explain the difference between non-persistent and persistent protocol.
Problem 5 (15)
Suppose within your Web browser you click on a link to obtain a Web
page. Suppose that the IP address for the associated URL is not cached
in your local host, so that a DNS lookup is necessary to obtain the IP
address. Suppose that n DNS servers are visited before your host
receives the IP address from DNS; the successive visits incur an RTT
of RRT_1, ..., RTT_n. Further suppose that the Web page associated
with the link contains exactly one object, a small amount of HTML
text. Let RTT_0 denote the RTT between the local host and the server
containing the object. Assuming zero transmission time of the object,
how much time elapses from when the client clicks on the link until
the client receives the object?
Suppose the HTML file indexes three very small objects on the same
server. Neglecting transmission times, how much time elapses with (1)
nonpersistent HTTP with no parallel TCP connections, (2) nonpersistent
HTTP with parallel connections, (3) persistent HTTP with pipelining?
Problem 6 (15)
Use socket programming to implement a public-key algorithm using RSA. Refer to problem 14 on page 831.