Yarmouk University
Hijjawi Faculty for Engineering Technology
Computer Engineering Department
CPE-562: Computer Networks
First Midterm Exam: A
Date: 13/11/11
Student Name
:------------------------------------------------------------------------------------------
Student Number:------------------------------------------------------------------------------------------
INSTRUCTIONS (please read carefully)
1.
2.
3.
4.
5.
TURN OFF YOUR CELL PHONE NOW
Time allowed 60 minutes
Provide your answers on this page. Answers elsewhere will not be looked at.
Return all pages.
Provide only one answer to each question. Giving more than one answer for the same
question will result in zero credit for that question.
6. Mark the right answer with (×).
A
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B
C
D
E
A
1
2
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B
C
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E
1.
2.
3.
4.
5.
How many layers does the host processes? Assume the
Internet architecture model.
a.
1
b. 2
c.
3
d. 4
e. 5
_____________ is a hidden devious part of some
otherwise useful software.
a.
Virus
b. Worm
c.
Spyware
d. Trojan horse
e. Botnet
Consider an application that transmits data with a
bursty nature:
a.
A circuit-switching network is more
appropriate for this application
b. A packet-switching network is more
appropriate for this application
c.
A circuit-switching network is as good as
packet-switching network for this
application
d. Neither circuit-switching network nor
packet-switching network is good for this
application
e. The information given in the statement
above is not sufficient to choose any of the
given answers
What does IETF stand for?
a.
Internet Engineering Task force
b. Internet Electronic Transmission Function
c.
Instant Electronic Transmission Form
d. Insecure Electronic Transaction Flag
e. Internet Electronic Transmission Forum
Consider the following HTTP request message. What is
the URL of the document requested by the browser?
GET /index.html HTTP/1.1\r\n
Host: www-net.cs.umass.edu\r\n
User-Agent: Firefox/3.6.10\r\n
Accept:
text/html,application/xhtml+xml\r\n
Accept-Language: en-us,en;q=0.5\r\n
Accept-Encoding: gzip,deflate\r\n
Accept-Charset: ISO-8859-1,utf8;q=0.7\r\n
Keep-Alive: 115\r\n
Connection: keep-alive\r\n
\r\n
a.
b.
c.
d.
e.
2|4
www-net.cs.umass.edu
/index.html
www-net.cs.umass.edu/index.html
Firefox/3.6.10
text/html,application/xhtml+xml
6.
Which of the following cannot be a host?
a.
Router
b. Server
c.
Cell phone
d. Desktop computer
e. Laptop computer
(Questions 7-8) Consider a message that is 1 M bits long that is to
be sent from source to destination in the figure below. Suppose
each link is 4 Mbps. Ignore propagation, queuing, and processing
delays.
7.
Consider sending the message from source to
destination without message segmentation. Assume
that each switch uses store-and-forward packet
switching, what is the total time to move the message
from source host to destination host?
a.
0.25 s
b. 1 s
c.
750 ms
d. 100 ms
e. 500 ms
8. Suppose now that the message is segmented into 500
packets, with each packet being 2000 bits long. How
long does it take to move the file from source host to
destination host when message segmentation is used?
a.
1001 ms
b. 251 ms
c.
125 ms
d. 50 ms
e. 1004 ms
9. Which of the following application layer protocols uses
UDP?
a.
HTTP
b. FTP
c.
SMTP
d. DNS
e. None of the given choices
10. Which of the following statements is wrong?
a.
FTP sends control information out-of-band
b. Cookies are used by e-commerce websites
to keep a purchase record for each
customer
c.
Network architecture and application
architecture are two different things
d. For a P2P file-sharing application, there is
no notion of client and server sides of a
communication session
e. Web caching reduces the delay for all
objects requested by a user, not only some
of the objects
11. Which of the following statements is wrong?
a.
An HTTP message with a status code 200
OK could be sent as a response to an HTTP
conditional GET with If-modified-since:
header line
b. FTP allows a client to browse a remote
directory by sending commands over
control connection
c.
Mail servers keep outgoing (to be sent) mail
messages in mailboxes
d. MAIL FROM: in SMTP and From: in the mail
message itself are two different things
e. The IP address of the host on which the
browser is running is not included in the
HTTP request message
12. What does URL stand for?
a.
Universal Record Link
b. Unspecified Record Location
c.
User Remote Login
d. User Requested Location
e. Uniform Resource Locator
13. Which of the following statements is correct?
a.
SMTP uses non-persistent connections
b. SMTP is a “pull” protocol
c.
SMTP sends multiple objects in a multipart
message
d. SMTP server uses CRLF. to determine end of
message
e. Some of the SMTP commands are non ASCII
14. Consider the following POP3 script. Which of the
following statements is wrong?
S: +OK POP3 server ready
C: user bob
S: +OK
C: pass hungry
S: +OK user successfully logged on
C: list
S: 1 498
S: 2 912
S: .
C: retr 1
S: <message 1 contents>
S: .
C: dele 1
C: retr 2
S: <message 1 contents>
S: .
C: dele 2
C: quit
S: +OK POP3 server signing off
a.
b.
c.
d.
e.
3|4
The user and pass are commands issued by
the client during the authorization phase
The user has two messages in her mailbox
The size of the second message is 912 bytes
This example uses “download and keep”
mode of POP3
POP3 is stateful across this session
15. Which of the following DNS servers act as DNS
registrar?
a.
Root DNS Servers
b. Top-level domain (TLD) servers
c.
Authoritative DNS servers
d. Local Name Servers
e. Any of the given answers
16. What type of DNS records, the name is alias name for
some “canonical” (the real) name?
a.
A
b. CNAME
c.
MX
d. NS
e. HINFO
17. What is the maximum data rate that a home user can
get using a dial-up modem?
a.
8 kbps
b. 56 kbps
c.
64 kbps
d. 1.544 Mbps
e. 3.152 Mbps
18. What type of media is most commonly used in LANs
nowadays?
a.
CAT 3 twisted pair
b. CAT 5 twisted pair
c.
Baseband Coaxial
d. Broadband Coaxial
e. Fiber Optic
19. What is the main problem that faces packet switching?
a.
It uses statistical multiplexing
b. No resource sharing
c.
No call setup
d. Congestion
e. None of the given choices
20. Which of the following “Internet architecture” layers is
responsible for routing of datagrams from source to
destination?
a.
Physical
b. Link
c.
Network
d. Transport
e. Application
21. Which of the following services, the TCP does not
provide?
a.
Connection oriented
b. Reliable transport
c.
Security
d. Flow control
e. Congestion control
22. Which of the following applications prefers UDP?
a.
File transfer
b. Streaming multimedia
c.
Remote terminal access
d. E-mail
e. Web
23. Which of the following servers holds resource records?
a.
Name server
b. Mail server
c.
Proxy server
d. HTTP server
e. Web server
24. Which of the following HTTP methods asks server to
leave requested object out of response
a.
DELETE
b. HEAD
c.
PUT
d. GET
e. POST
25. Consider the following HTTP reply message sent from a
server in response to an HTTP GET message. What are
the first 5 bytes of the document being returned?
HTTP/1.1 200 OK <cr><lf>Date: Tue, 07
Mar 2006
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-f22a88a4c80"<cr><lf>AcceptRanges: 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="ContentType"
content="text/html; charset=iso-88591"><lf> <meta
name="GENERATOR"
content="Mozilla/4.79 [en] (Windows
NT
5.0; U) Netscape]"><lf> <title>CMPSCI
453 / 591 /
NTU-ST550A Spring 2005
homepage</title><lf></head><lf>
<much more document text following
here (not shown)>
a.
b.
c.
d.
e.
4|4
<!doc
Mozil
Windo
NTU-S
HTTP/