FINALTERM EXAMINATION Fall 2008 CS610- Computer Network

FINALTERM EXAMINATION Fall 2008
CS610- Computer Network
Question No: 21      ( Marks:2)
Is there a comparison between TCP/IP reference model and OSI reference model?
Answer:- rep
Question No: 22      ( Marks:2)
How can a datagram be transmitted across a physical network that does not understand the datagram
format?
Answer:- rep
Question No: 23      (Marks:2)
What is the basic concept of Twice NAT (Network Address Translation)?        
Answer:- rep
Question No: 24      ( Marks:3)
What format is used for an internet packet?
Answer:- (CS610 ref.Book  Page 37)
The internet layer defines an official packet format and protocol called IP (Internet Protocol). The job of the
internet layer is to deliver IP packets where they are supposed to go.
Question No: 25      ( Marks:3)
“To achieve a hierarchy, OSPF allows an autonomous system to be partitioned for routing purposes”.
Does this feature make OSPF more complex or powerful?
Answer:- Click here for detail
OSPF allows an autonomous system to be partitioned for routing purposes which make it complex but More
powerful.
Question No: 26      ( Marks:3)
Why does IPv6 use separate Extension Headers?
Answer:- (Page 113)
IPv6 use separate Extension Headers. Fragmentation information is kept in separate extension header. Each
fragment has base header and (inserted) fragmentation header. Entire datagram including original header may
be fragmented.
Question No: 27      ( Marks:5)
Consider the IP addresses: 178.200.127.5 and the corresponding subnet masks 255.255.255.0, then find
out the following:
a.       The number of bits used for subnetting
b.      Total number of host in the subnet
c.       The network address of the subnet
d.       The subnet address of the IP address.28
Answer:-  Click here for detail
a. The number of bits used for subnetting
Answer
8 bits
b. Total number of host in the subnet
Answer
254
c. The network address of the subnet.
Answer
178.200.127.0
Question No: 28      ( Marks:5)
How does IP software reassemble fragments that arrive out of order?
Answer:-  rep
Question No: 29      (Marks:5)
Write down the comparison of Distance- vector and Link – state algorithm?
Answer:- (Page 64)
COMPARISON:
DISTANCE-VECTOR ROUTING:
• It is very simple to implement.
• Packet switch updates its own routing table first.
• It is used in RIP.
LINK-STATE ALGORITHM:
• It is much more complex.
• Switches perform independent computations.
• It is used in OSPF.
Question No: 30      ( Marks:10)
Describe in detail what is the purpose of the following table? What sort of information can be extracted?
First Four Bits
Of address
Table index in
decimal
Class of Address
0000 0 A
0001 1 A
0010 2 A
0011 3 A
0100 4 A
0101 5 A
0110 6 A29
0111 7 A
1000 8 B
1001 9 B
1010 10 B
1011 11 B
1100 12 C
1101 13 C
1110 14 D
1111 15 E
Answer:- (Page 87)
Whenever it handles a packet, IP software needs to separate the destination address into a prefix and suffix.
Classful IP addresses are self-identifying because the class of the address can be computed from the address
itself. The table shows in the figure above how the class of address can be computed.
Question No: 31      (Marks: 10)
List down and describe at least five characteristics of Routing Information Protocol.
Answer:- (Page 138)
ROUTING INFORMATION PROTOCOL (RIP):
It has the following characteristics:
"It is used for routing within an autonomous system (IGP).
"It uses UDP for all message transmissions.
"It can be used to advertise default route propagation. An organization can use RIP to install a default route in
each router.
"It uses distance vector algorithm.
"RIP allows hosts to listen passively and update its routing table.