Test Bank Questions and Answers for computer network chapter 2 Rated A+
For a communication session between a pair of processes, which process is the client and which is the
server? - Answers The process which initiates the communication is the client; the process that waits to
be contacted is the server.
What is meant by a handshaking protocol? - Answers A protocol uses handshaking if the two
communicating entities first exchange control packets before sending data to each other. SMTP uses
handshaking at the application layer whereas HTTP does not.
Describe how Web caching can reduce the delay in receiving a requested object. Will Web caching
reduce the delay for all objects requested by a user or for only some of the objects? Why? - Answers
Web caching can bring the desired content "closer" to the user, perhaps to the same LAN to which the
user's host is connected. Web caching can reduce the delay for all objects, even objects that are not
cached, since caching reduces the traffic on links.
In BitTorrent, suppose Alice provides chunks to Bob throughout a 30-second interval. Will Bob
necessarily return the favor and provide chunks to Alice in the same interval? Why or why not? -
Answers It is not necessary that Bob will also provide chunks to Alice. Alice has to be in the top 4
neighbors of Bob for Bob to send out chunks to her; this might not occur even if Alice provides chunks to
Bob throughout a 30 second interval.
What is an overlay network? Does it include routers? What are the edges in
the overlay network? - Answers Overlay Network is a logical network that runs on top of another
network.
No, it does not include routers.
If peer X maintains a TCP connection with another peer Y, then we say there is an edge between X and Y.
An edge in overlay is simply the tcp connection between a peer.
In Section 2.7, the UDP server described needed only one socket, whereas the
TCP server needed two sockets. Why? If the TCP server were to support n
simultaneous connections, each from a different client host, how many sockets
would the TCP server need? - Answers With the UDP server, there is no welcoming socket, and all data
from different clients enters the server
through this one socket. With the TCP server, there is a welcoming socket, and each time a client
initiates
a connection to the server, a new socket is created. Thus, to support n simultaneous connections, the
server
, would need n + 1 sockets.
The text below shows the reply sent from the
server in response to the HTTP GET message in the question above. Answer the
following questions, indicating where in the message below you find the answer.
HTTP/1.1 200 OK<cr><lf>Date: Tue, 07 Mar 2008 12:39:45GMT<cr><lf>Server:
Apache/2.0.52 (Fedora)<cr><lf>Last-Modified: Sat, 10 Dec2005 18:27:46
GMT<cr><lf>ETag: "526c3-f22-a88a4c80"<cr><lf>Accept-Ranges:
bytes<cr><lf>Content-Length: 3874<cr><lf> Keep-Alive:
timeout=max=100<cr><lf>Connection:Keep-Alive<cr><lf>Content-Type: text/html;
charset=ISO-8859-1<cr><lf><cr><lf><!doctype html public "-//w3c//dtd html 4.0
transitional//en"><lf><html><lf><head><lf> <meta http-equiv="Content-Type"
content="text/html; charset=iso-8859-1"><lf> <meta name="GENERATOR"
content="Mozilla/4.79 [en] (Windows NT 5.0; U) Netscape]"><lf> <title>CMPSCI
/NTU-ST550A Spring 2005 homepage</title><lf></head><lf><much more
document - Answers a. The status code of 200 and the phrase OK indicate that the server was able to
locate the
document successfully. The reply was provided on Tuesday, 07 Mar 2008 12:39:45
Greenwich Mean Time.
b. The document index.html was last modified on Saturday 10 Dec 2005 18:27:46 GMT.
c. There are 3874 bytes in the document being returned.
d. The first five bytes of the returned document are : <!doc. The server agreed to a
persistent connection, as indicated by the Connection: Keep-Alive field
Referring to Problem P7, suppose the HTML file references eight very small objects on the same
server. Neglecting transmission times, how much time elapses with
a. Non-persistent HTTP with no parallel TCP connections?
b. Non-persistent HTTP with the browser configured for 5 parallel connections?
For a communication session between a pair of processes, which process is the client and which is the
server? - Answers The process which initiates the communication is the client; the process that waits to
be contacted is the server.
What is meant by a handshaking protocol? - Answers A protocol uses handshaking if the two
communicating entities first exchange control packets before sending data to each other. SMTP uses
handshaking at the application layer whereas HTTP does not.
Describe how Web caching can reduce the delay in receiving a requested object. Will Web caching
reduce the delay for all objects requested by a user or for only some of the objects? Why? - Answers
Web caching can bring the desired content "closer" to the user, perhaps to the same LAN to which the
user's host is connected. Web caching can reduce the delay for all objects, even objects that are not
cached, since caching reduces the traffic on links.
In BitTorrent, suppose Alice provides chunks to Bob throughout a 30-second interval. Will Bob
necessarily return the favor and provide chunks to Alice in the same interval? Why or why not? -
Answers It is not necessary that Bob will also provide chunks to Alice. Alice has to be in the top 4
neighbors of Bob for Bob to send out chunks to her; this might not occur even if Alice provides chunks to
Bob throughout a 30 second interval.
What is an overlay network? Does it include routers? What are the edges in
the overlay network? - Answers Overlay Network is a logical network that runs on top of another
network.
No, it does not include routers.
If peer X maintains a TCP connection with another peer Y, then we say there is an edge between X and Y.
An edge in overlay is simply the tcp connection between a peer.
In Section 2.7, the UDP server described needed only one socket, whereas the
TCP server needed two sockets. Why? If the TCP server were to support n
simultaneous connections, each from a different client host, how many sockets
would the TCP server need? - Answers With the UDP server, there is no welcoming socket, and all data
from different clients enters the server
through this one socket. With the TCP server, there is a welcoming socket, and each time a client
initiates
a connection to the server, a new socket is created. Thus, to support n simultaneous connections, the
server
, would need n + 1 sockets.
The text below shows the reply sent from the
server in response to the HTTP GET message in the question above. Answer the
following questions, indicating where in the message below you find the answer.
HTTP/1.1 200 OK<cr><lf>Date: Tue, 07 Mar 2008 12:39:45GMT<cr><lf>Server:
Apache/2.0.52 (Fedora)<cr><lf>Last-Modified: Sat, 10 Dec2005 18:27:46
GMT<cr><lf>ETag: "526c3-f22-a88a4c80"<cr><lf>Accept-Ranges:
bytes<cr><lf>Content-Length: 3874<cr><lf> Keep-Alive:
timeout=max=100<cr><lf>Connection:Keep-Alive<cr><lf>Content-Type: text/html;
charset=ISO-8859-1<cr><lf><cr><lf><!doctype html public "-//w3c//dtd html 4.0
transitional//en"><lf><html><lf><head><lf> <meta http-equiv="Content-Type"
content="text/html; charset=iso-8859-1"><lf> <meta name="GENERATOR"
content="Mozilla/4.79 [en] (Windows NT 5.0; U) Netscape]"><lf> <title>CMPSCI
/NTU-ST550A Spring 2005 homepage</title><lf></head><lf><much more
document - Answers a. The status code of 200 and the phrase OK indicate that the server was able to
locate the
document successfully. The reply was provided on Tuesday, 07 Mar 2008 12:39:45
Greenwich Mean Time.
b. The document index.html was last modified on Saturday 10 Dec 2005 18:27:46 GMT.
c. There are 3874 bytes in the document being returned.
d. The first five bytes of the returned document are : <!doc. The server agreed to a
persistent connection, as indicated by the Connection: Keep-Alive field
Referring to Problem P7, suppose the HTML file references eight very small objects on the same
server. Neglecting transmission times, how much time elapses with
a. Non-persistent HTTP with no parallel TCP connections?
b. Non-persistent HTTP with the browser configured for 5 parallel connections?
