CSCI 547 Computer Networks Final Exam
FALL 2007
Closed book, closed
notes. Some questions have
multiple answers!
There are more than
100 points. Answer all questions!
Name:___________________________________
1.(6 points) IEEE 802 protocols
Match the following
802 protocols with a description. Draw lines between them.
|
802.1 802.2 802.3 802.11 802.3u 802.3z |
|
Wireless Access Protocol
& Physical layer 100M bps Ethernet 1000M bps Ethernet Higher layer interface to
802 protocols Logical Link Control CSMA/CD & Physical
layer |
2.(5 points) Connection-oriented service’s
responsibilities are:
Choose all that
apply.
|
|
a. |
Initialization of the connection |
|
|
b. |
Error detection using CRC code |
|
|
c. |
Resetting the link in case of an error |
|
|
d. |
Flow control |
|
|
e. |
Termination of the connection |
|
|
f. |
Sending a “keep alive” messages to keep the link intact |
|
|
g. |
Retransmit a message in case of timeout |
3.(1 points) Dotted decimal notation
Given the following
IP address in binary, what is its dotted decimal equivalent?
10000100 11110001
10011110 00100111
|
|
a. |
132.243.148.32 |
|
|
b. |
123.142.150.36 |
|
|
c. |
132.241.158.39 |
|
|
d. |
132.241.156.38 |
4.(6 points) Subnet masks
For the subnetting scheme which allows all 0’s and all 1’s subnetids(as in CIDR), choose all the possible subnet
masks.
|
|
a. |
64 |
|
|
b. |
128 |
|
|
c. |
192 |
|
|
c. |
220 |
|
|
d. |
224 |
|
|
e. |
240 |
|
|
f. |
242 |
|
|
g. |
248 |
|
|
h. |
250 |
|
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i. |
252 |
|
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j. |
254 |
|
|
k. |
255 |
5.(1 points) Identify IP address
Identify the following
IP address: 132.241.255.255
|
|
a. |
host IP address |
|
|
b. |
direct broadcast address |
|
|
c. |
limited broadcast address |
|
|
d. |
network address |
6.(1 points) Identify IP address
Identify the following
IP address: 255.255.255.255
|
|
a. |
host IP address |
|
|
b. |
direct broadcast address |
|
|
c. |
limited broadcast address |
|
|
d. |
network address |
7.(2 points) Getting IP address
A host can get its
IP address from its DHCP server by using _____ as the source address and ____
as the destination address.
|
|
a. |
255.255.255.255 ; 127.0.0.1 |
|
|
b. |
127.127.127.127 ; 0.0.0.0 |
|
|
c. |
0.0.0.0 ; 255.255.255.255 |
|
|
d. |
255.255.255.255 ; 0.0.0.0 |
|
|
e. |
none of the above |
8.(3 points) TCP/IP configuration
Among many
configuration parameters, which three(3) are the most essential settings for
TCP/IP networking?
|
|
a. |
IP address |
|
|
b. |
WINS server |
|
|
c. |
Subnet mask |
|
|
d. |
Default Gateway |
|
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e. |
DNS server address |
|
|
f. |
Computer’s name |
9.(3 points) Through a
router?
A host with IP
address 132.241.158.70 with subnet mask of 255.255.255.240 sends a message
to a host with IP address 132.241.158.60. Does the message travel through any
router?
|
|
a. |
Yes |
|
|
b. |
No |
10.(3 points) Through a
router?
A host with IP
address 132.241.158.35 and subnet mask 255.255.255.224 sends a message to a host
with IP address 132.241.158.52. Does the message travel through any router?
|
|
a. |
Yes |
|
|
b. |
No |
11.(4 points) Supernet mask
Which one should be
the "supernet mask" to combine 32 class C network addresses?
|
|
a. |
255.255.255.192 |
|
|
b. |
255.255.252.0 |
|
|
c. |
255.255.248.0 |
|
|
d. |
255.255.240.0 |
|
|
e. |
255.255.224.0 |
|
|
e. |
255.255.192.0 |
12.(2 points)Default mask
Which of the
following is the default subnet mask(before any subnetting is done) for the address 80.1.2.3?
|
|
a. |
255.0.0.0 |
|
|
b. |
255.255.0.0 |
|
|
c. |
255.255.255.0 |
|
|
d. |
255.255.255.224 |
13.(3 points) How many hosts
per subnet?
A subnet mask of
255.255.255.248 allows how many hostids per subnet?
|
|
a. |
16 |
|
|
b. |
8 |
|
|
c. |
6 |
|
|
d. |
2 |
14.(1 points) Fragmentations
When a router
cannot deliver an IP datagram in its original size, the router fragments IP
datagram into several fragments. Who is responsible for reassembling the
fragments?
|
|
a. |
Router at the destination network |
|
|
b. |
All intervening routers where fragments occur |
|
|
c. |
Destination host |
15.(3 points) IPv6
What are the main
improvements in IPv6 over IPv4? Choose all that apply.
|
|
a. |
Larger address space |
|
|
b. |
Smaller header size |
|
|
c. |
More elaborate error checking on the header portion |
|
|
d. |
Provides better Quality of Service features |
|
|
e. |
With IPv6, we do not need MAC addresses anymore |
16.(3 points)
When you issue
“ping 127.0.0.1” in Command Prompt window, you are checking what?
17.(5 points) The
table for Special IP addresses are given below. The first column is left blank.
Select the right kind of special address for each row. The list of special
address is given below:
(a) Specific host on this network
(b) Limited broadcast address
(c) Network
address
(d) Loopback
address
(e) Direct broadcast address
(f) This
host on this network
Special Addresses Netid Hostid Source or Destination
---------------------------------------------------------------------------------------------------------
Specific All 0s None
---------------------------------------------------------------------------------------------------------
Specific All 1s Destination
---------------------------------------------------------------------------------------------------------
All
1s All 1s Destination
---------------------------------------------------------------------------------------------------------
All
0s All 0s Source
---------------------------------------------------------------------------------------------------------
All
0s Specific Destination
---------------------------------------------------------------------------------------------------------
127 Any Destination
18.(4 points) Why do we need subnetting?
19.(4 points) What is the main difference between
“classful IP subnetting” and “CIDR”?
20.(6 points) There are 4 ways(considering IPv6 also)
of sending IP packets. One is “unicast”. Name the other three and explain each
clearly.
21.(4 points) RIP vs OSPF
What are the main advantages
of OSPF over RIP?
22.(10 POINTS) Mail access protocols
There are three Mail access protocols(for the retrieval
of e-mails from mail server). Point out
the differences between them.
v POP: Post Office Protocol
v IMAP: Internet Mail Access Protocol
v HTTP(web based):
23.(4 points) Solutions to IP address space?
Fill in the blanks.
IP address space
for IPv4 is running out. There is short term solutions and long term solution.
The three short
term solutions are:
a)_______________________________
b)_______________________________
c)_______________________________
The long term solution
is _________________
24.(4 points) Describe how DHCP works. Describe all
the interactions between a DHCP client and a DHCP server.
25.(4 points) To solve the problem of increasing size
of routing tables, CIDR uses ‘route aggregation”. Describe.
26.(9 points)VLSM example:
Suppose the following:
q We need to use all 0’s & all 1’s subnets to fully utilize address space
q A company is assigned a class C address space and needs the following:
|
# of subnets |
subnet size |
purpose |
|
2 |
60+
hosts |
For 2 main offices |
|
4 |
10+
hosts |
For 2 branch offices & 2 server
farms |
|
The rest |
2
hosts |
PPP (for telecommuting) |
In the above diagram, the values of 3 subnet masks are left blank. Fill in
the blanks.
27.(8 points)For the transition period
from IPv4 to IPv6, there are two approaches.
a) Fill
in the blanks:
They are 1) ____________________ 2)______________________
b) Explain
each of the above:
1)
2)
28.(10 points) Fill in
the diagram of TCP/IP protocol stack. List all protocols on each layer(also show the protocols that are at the boundary
of layers):
|
OSI Layer number |
TCP/IP Protocols |
|
Layer 7 |
|
|
Layer 6 |
|
|
Layer 5 |
|
|
Layer 4 |
|
|
Layer 3 |
|
|
Layer 2 |
Not defined in
TCP/IP—defined in IEEE803 |
|
Layer 1 |
Not defined in
TCP/IP—defined in IEEE803 |
29.(4 points) What are
the two main reasons for the domination of Ethernets in LAN technology?
30.(4 points) Fill in the blanks:
The advantages of RIP protocol are simplicity and low overhead. RIP has
three disadvantages:
1)
The limit to the size of a network
imposed by maximum hop count(15).
2)
______________________________________________
3)
______________________________________________
31.(5 points)
BGP protocol uses Path
Vectors in the routing calculations. A Path Vector is a list of
______________ numbers
in a path.
Describe how CRC error
checking code works. Here, we will use decimal numbers for the sake of
simplicity. Fill in the blanks:
A sender divides the
information(a decimal number) by a ____________ and the
_________ is attached
to the information.
The receiver uses the
same __________ and compares the results. If the calculated
_________ is the same as the one sent by
sender, then NO Error!.
32.(3 points) Describe
how ARP protocol works. Include the following words:
·
MAC address
·
IP address
·
Broadcast
·
Unicast
·
ARP cache
33.(3 points) Describe
how “autonegotiation works”.
34.(3 points) What is
the main difference between a hub and a switch?
35.(3 points) What are
the most valuable things you learned in this course?