Sunday 29 July 2012

CS610 Final 2010 - Computer Network - Solved with Ref 2


Time: 120 min
M = Marks = 70


Question No: 1      ( M - 1 )
The number of connections needed for N computer in direct point to point communication is equal to:

► (N2 –N)/2
► N(N- 1)
► N2
► None of the given

Question No: 2      ( M - 1 )
When an application--------------- data, it makes a copy of the data available to all other computers on the network.

► Broadcasting
► Multicasting
► Unicasting
► None of the given

Question No: 3      ( M - 1

Ethernet uses a ------ bit static addressing scheme in which each device is assigned a unique address by the manufacturer.

► 64
► 48
► 32
► 8

Question No: 4      ( M - 1 )
A system with redundant bridges might have a problem with_______ in the system.
► Loop
► Filters
► Spanning Trees
► All given choices

Question No: 5      ( M - 1 )
The product of delay and throughput measures the _____ of data that can be present on the network.

► Area
► Volume
► Length
► None of the given


Question No: 6      ( M - 1 )
Connectionless service, Message-Oriented protocol, best effort delivery service, arbitrary interaction and operating system independent are the characteristics of _____________

► TCP
► UDP
► IP
► None of the given

Question No: 7      ( M - 1 )

Connection-oriented service, Point-to-point, Complete reliability, Full-duplex communication, Stream interface, Reliable connection startup and Graceful connection shutdown are the services provided by__________
► None of the given
► TCP
► UDP
► IP
SERVICE PROVIDED BY TCP:
Following are the services provided by TCP:
• Connection-oriented service
• Point-to-point
• Complete reliability
• Full-duplex communication
• Stream interface
• Reliable connection startup
• Graceful connection shutdow


Question No: 8      ( M - 1 )

The process of using a routing table to select a next hop for a given datagram is called_________

► Encapsulation
► Reassembling
► Routing or forwarding
► None of the given
The process of using a routing table to select a next hop for a given datagram is called routing or forwarding.

Question No: 9      ( M - 1 )

____________ uses distance vector approach to define routing

► BGP
► OSPF
► RIP
► None of the given

DISTANCE-VECTOR ROUTING:
• It is very simple to implement.
• Packet switch updates its own routing table first.
• It is used in RIP

Question No: 10      ( M - 1 )

A multicast routing scheme in which the protocol software builds a delivery tree from a central point is called__________

► Distance Vector Multicast Routing Protocol (DVMRP)
► Core Based Trees (CBT)
► Protocol Independent Multicast_ Sparse Mode (PIM-SM)
► Protocol Independent Multicast _ Dense Mode (PIM-DM)

Core Based Trees (CBT): The protocol software builds a delivery tree from a central point

Question No: 11      ( M - 1 )
One repeater _______, two repeaters ________ the maximum cable length limitation.
► doubles, cancel
► doubles, triple
► square roots, cude roots
► and, triple

Question No: 12      ( M - 1 )

Whenever it handles a packet, IP software needs to separate the destination address into a _________ and ___________.
► postfix, Infix
► non of these
► Infix, prefix
► prefix, suffix
Whenever it handles a packet, IP software needs to separate the destination address into a prefix and suffix

Question No: 13      ( M - 1 )

Although message exchange can be used to bind addresses, sending a request for each binding is hopelessly inefficient.
► True
► False
Although message exchange can be used to bind addresses, sending a request for
each binding is hopelessly inefficient.


Question No: 14      ( M - 1 )

ARP is almost always used to bind a ___-bit IP address to a ___-bit Ethernet address.
► 32, 48
► 24, 32
► 32, 64
► 32, 128
ARP is almost always used to bind a 32-bit IP addressto a 48-bit Ethernet ad

Question No: 15      ( M - 1 )

End-to-end delivery service is connection oriented.
► True
► False

End-to-end delivery service is connection less

Question No: 16      ( M - 1 )
A single networking technology is best for all needs.
► True
► False
here is no single networking technology that is best for all needs
Question No: 17      ( M - 1 )

In the 1970s large organizations began to acquire multiple networks. Each network in the organization formed island. Employees needed to choose a computer appropriate for each task. So they needed multiple screens, keyboards and computers.

► False
► True

n the 1970s large organizations began to acquire multiple networks. Each network in the organization formed island. Employees needed to choose a computer appropriate for each task. So they needed multiple screens, keyboards and computers.
Question No: 18      ( M - 1 ) \

Which method of Address Resolution Protocol is useful with any hardware?
Were "T" stands for Table lookup, "C" for Closed-form Computation and "D" for Data Exchange?

► T
► C
► D
► C, D
Features

Types of
Resolution
Use full with any hardware    T
Address change affects all hosts        T
Protocol address is determined by hardware address            C

Question No: 19      ( M - 1 )
In which method of Address Resolution Protocol the protocol address is determined by hardware address?
Were "T" stands for Table lookup, "C" for Closed-form Computation and "D" for Data Exchange?
► T
► D
► C
► T, C

Question No: 20      ( M - 1 )

We use the term _______ to refer to a measure of the path that routing software use when choosing a route.
► routing path
► routing metric
► routing
► switching
We use the termrouting metric to refer to a measure of the path that routing software use when choosing a route
Question No: 21      ( M - 2 )

Is there a comparision between  TCP/IP reference model and ISO reference model.

Question No: 22      ( M - 2 )

Does OSPF only share information within an area or does it allow communication between areas?
OSPF allows subdivision of Autonomous System into areas. The link-status information is propagated within an area. The routes are summarized before being propagated to another area. It reduces overhead (less broadcast traffic). Because it allows a manager to partition the routers and networks in an autonomous system into multiple areas, OSPFcan scale to handle a larger number of routers than other IGPs.

Question No: 23      ( M - 2 )

What are the implimentations of Network Address Translation?

Question No: 24      ( M - 3 )
 Describe the difference between static and dynamic routing?

STATIC ROUTING:
It is one of the forms of Internet routing. In Static routing, the table is initialized
when system boots and there is no further changes.
DYNAMIC ROUTING:
In dynamic routing the table is initialized when system boots. It includes routing
software which learns routes and updates table. In this way continuous changes are
possible due to routing software.

Question No: 25      ( M - 3 )

What is the first address in the block if one of the addresses is 140.120.84.24/20?
The first address in the block is 140.120.80.0/20
WE can use the following short cut to find the first address
divide the prefix length into four groups(corresponding to the four bytes in an address) and find the number of 1s in each group
if the number of 1s in a group is 8 the corresponding byte in the first address is the same (no change)
If the number of 1s in the group is zero (no1s), the corresponding byte in the first address is 0
if the number of 1s in a group is between zero and eight, we keep the corresponding bits in that group


Question No: 26      ( M - 3 )

Write three new features of IPV6.
• IPV6 addresses are 128 bits.
• Header format is entirely different.
• Additional information is stored in optional extension headers, followed by data.
• Flow label and quality of service allows audio and video applications to establish
appropriate connections.
• New features can be added more easily. So it is extensible.


Question No: 27      ( M - 5 )

What is the difference between an interior gateway protocol and an exterior gateway protocol? Name an example of each.

INTERIOR GATEWAY PROTOCOLS (IGPs):
It is used among routers within autonomous system. The destinations lie within IGP.
EXTERIOR GATEWAY PROTOCOLS (EGPs):
It is used among autonomous systems. The destinations lie throughout Internet

Question No: 28      ( M - 5 )

As the Internet grew, the original Classful addressing scheme became a limitation, what is was the designed solution.

Question No: 29      ( M - 5 )

What are IPv6 ADDRESS NOTATION?
IPv6 ADDRESS NOTATION:
128-bit addresses unwidely in dotted decimal; requires 16 numbers:
105.220.136.100.255.255.255.255.0.0.18.128.140.10.255.255
Groups of 16-bit numbers in hex separated by colons – colon hexadecimal (or colon hex).
69DC: 8864:FFFF: FFFF: 0:1280:8C0A:FFFF
Zero-compression – series of zeroes indicated by two colons
FF0C: 0:0:0:0:0:0:B1
FF0C::B1
IPv6 address with 96 leading zeros is interpreted to hold an IPv4 address.
Question No: 30      ( M - 10 )
LIST SOME CHARACTERISTICS OF A CLIENT.



CHARACTERISTICS OF A CLIENT:

The characteristics of a client are explained below:

"Client is an arbitrary application program.

"It becomes client temporarily.

"It can also perform other computations.



"It is invoked directly by the user.



"It runs locally on the user’s computer.



"It actively initiates contact with a server.



"It contacts one server at a time.

Question No: 31      ( M - 10 )
With help of the diagram below, explain TCP Segment Format:



TCP uses single format for all messages. TCP uses the term segment to refer to a message. Each message sent from TCP on onemachine to TCP on another machine uses this format including data andacknowledgement


Field Name
Size (bytes)
Description
SourcePort
2
ephemeral (client) port numberSourcePort: The 16-bit port number of the process that originated the TCP segment on the source device. This will normally be an for a request sent by a client to a server
DestinationPort
2
DestinationPort: The 16-bit port number of the process that is the ultimate intended recipient of the message on the destination device.
Sequence Number
4
Sequence Number: For normal transmissions, the sequence number of the first byte of data in this segment. In a connection request (SYN) message, this carries the initial sequence number (ISN) of the source TCP.
Acknowledgment Number
4
Acknowledgment Number: When the ACK bit is set, this segment is serving as an acknowledgment (in addition to other possible duties) and this field contains the sequence number the source is next expecting the destination to send.
Window
2
Window: Indicates the number of octets of data the sender of this segment is willing to accept from the receiver at one time. This normally corresponds to the current size of the buffer allocated to accept data for this connection.
Checksum
2
16-bit checksum for data integrity protectionChecksum: A , computed over the entire TCP datagram plus a special “pseudo header” of fields. It is used to protect the entire TCP segment against not just errors in transmission, but also errors in delivery.
Urgent Pointer
2
Urgent Pointer: Used in conjunction with the URG control bit for priority data transfer. This field contains the sequence number of the last byte of urgent data.
Options
Variable
Options: TCP includes a generic mechanism for including one or more sets of optional data in TCP segment. Each of the options can be either one byte in length or variable length. The first byte if the option kind subfield and it’s value specifies the type of option, which in turn indicates whether the option is just a single byte or multiple bytes. Options that are many bytes consist of three fields


Note this table is also included in options column. options may vary
Subfield name
Size (bytes)
Description
Option-kind
1
Option-kind: specifies the option type
Option-length:
1
Option-length: the length of the entire option in bytes, including the option-kind and option-length fields.
Option-data
Variable
Option-data: the option data itself in at least one oddbll case, this field is omitted(making option length equal to 2)

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