[This question paper contains 4 printed pages.]
Your Roll No..
Sr. No. of Question Paper : 6506
Unique Paper Code
Name
the
of
Paper
Name of the Course
HC
32341303
Computer Networks
:B.Sc. (H) Computer Scienee
Semester
Maximum Marks : 75
Duration : 3 Hours
instructions for Candidates
1.
Write your Roll No. on the top immediately on receipt of
this question paper
2.
a r t A is compulsory and carries 35 marks.
3.
Attempt any four questions from Part B.
PART A
1.
(a) Eight signals each requiring 2000 Hz are multiplexed on
to a single channel using FDM. How much minimum
bandwidth is required for the multiplexed channel
assuming guard bands are 200 Hz wide.
(2)
(b) What is the concept of Frequency Division Multiplexing?
(2)
P.T.O.
2
6506
6506
(c) Write down the three differences between OSI model
and TCP/IP model.
(n) Define th
(3)
(d) Evaluate the maximum bit
for
rate
) Broa.
channel having
andwidth 1600 Hz, if S/N ratio is 20db.
(2)
a
ii) Pig
(ii) Sel
(e) Write two features each of thick and thin Ethernet
LAN.
(2)
() Give the port number of following protocols:
(2)
2.
(a) Describ
TELNET, HTTP
How C
(g) How pipelining property is used in sliding window
protocols?
(b) Elabor
(2)
one
host.
(h) What is IP loop back address?
(2)
i) Give the frame format of Ethernet?
(2)
G) What is
n
(a) What
Ethe
a
URL? Write with
an
example.
(3)
be z
(k) A router inside an organization receives a packet with
(b) Giv
the destination address 190.240.34.95. If the subnet mask
is /19, find the subnet address.
(c) Ho
(2)
(1) At what layer(s) do the
TCP/IP protocol?
(i) DHCP
(ii) CSMA
(m) Define modulation
techniquuc.
net
following protocols operate
in
(4)
(ii)
giving
FTP
any
iv)
ICMP
4.
(a) Gi
fo
three modulation
(4)
6506
3
(n) Define the following terms
(i) Broadcasting
(ii) Piggybacking
(ii) Selective Flooding
(3)
PART B
2.
(a) Describe the various carries sense protocols. Explain
How CSMA/CD protocol works.
(3+2)
(b) Elaborate the technique used to allow programs on
one machine to call procedures located on remote
host.
3.
5)
(a) What are the minimum and maximum frame sizes for
Ethernet frames? Why can't the minimum frame length
be zero?
(b) Give the format for IP header.
(3)
(3)
(c) How is connection oriented service implemented at
network layer?
4.
(4)
(a) Give the pulse diagram for bit stream 101010101011.
for the following encoding techniques
(i) RZ
(ii) Manchester
P.T.O.
6506
4
(ii) Differential Manchester
(6)
(b) What are the advantages and
disadvantages of using
optical fiber as transmission media?
(4)
5.
(a) Explain the working of Dijkstra Algorithm and find out
the shortest distance from A to D according to it.
Distance between vertices
are as follows:
d(A,B)=2, d(A,F)=1, d{A,E)=4, d(B,C)=5, d(B,F)=3,
d(E.F)=1, d(C,D)=1, d(D,E)=3, d(F,G)=2, d(G,C)=1 and
d(G.D)=4.
(6)
(b) Explain TCP connection establishment and release
(4)
process.
6.
Write
(i)
a
short note
on
the
following:
(2x5)
HTTP
(ii) DNS
(l) DSL
(iv)
(v)
UDP
RARP
(1400)
(This question paper contains 7 printed pages]
Your Roll No.
S1. No. of Q.
:7405
Paper
J
Unique Paper Code
32341303
Name of the Course
B.Sc.(Hons.) Computer
Science
Name of the Paper
:Computer Networks
Semester
: III
Maximum Marks: 75
Time 3 Hours
Instructions for Candidates:
(a) Write your Roll No. on the top immediately
on receipt of this question paper.
(b)
Section-A is
marks.
compulsory and carries 35
(c) Attempt any four questions from Section-B.
Section-A
1.
(a)
A bit stream of 10111011 is to be
transmitted using the standard CRC method
x3+1 as the generator polynomial.
Show the actual bits transmitted. Suppose
the 4th bit from the left gets inverted due to
the error can be
an error, check whether
having
caught.
P.T.O.
7405
(b)
Ethernet requires that valid frames must be
at least 64 bytes long. Give reasons for
choosing the minimum frame size as 64
2
bytes.
(c) Convert the IP address whose hexadecimal
representation is C22F1582 to dotted
decimal representation. 194 41 2 130
1
(d) Explain briefly the following fields of the IP
header:
4
Internet Header
Length (IHL)
(ii) Identification,
(i) DF 8 MF, and
(iv) TTL
(e) Briefly discuss the following CSMA protocols
6
i) 1-persistence
(ii) p-persistence and
(iii) non-persistence
(f
Match the following to one or more layers of
theTCP/IP model
5
(i)
Transmission of bit stream across
physical medium
(ii)
Defines frames
2
405
(i) Reiiable process-to-process message
delivery
iv) Route Selection
(v)
Provides
user
services such
and file transfer
as email
t
(g) What is the baud rate of classic 10-Mbps
Ethernet?
(h)
2
20 mbps
Five channels, each with
a
100-kHz
bandwidth, are to be multiplexed together.
What is the minimum bandwidth of the link,
if there is a need for a guard band of 10-kHz
between
the
channels
to
prevent
3
interference ?
(i) What does the following address
mean
3
when are they used ?
(i)
0.0.0.0
lou
and
Lhost
Local ocp
(ii) 127.xx.yy.zz
(iii) 156.76.255.255B
3
1B-vedeas
P.T.O.
7405
G) Explain simplex, half-duplex, and full-duplex
3
modes of communication.
(k) State the Nyquist sampling theorem ilor
2
analog-to-digital conversion.
Section-B
2. (a) A system has an n-layer protocol hierarchy.
Applications generate messages of length M
bytes. At each of the layers, an h-byte
header is added. What fraction of the
network bandwidth is filled with headers?
3
(b) Explain the concept of byte stuffing used for
framing.
2
(c) Define bandwidth of a signal. A periodic
signal has a bandwidth of 20 Hz. The highest
frequency is 60 Hz. What is the lowest
frequency ?
7405
(d) What is the Nyquist sampling rate for each
of the following signals?
3
() A low-pass signal with bandwidth of 200
KHz?o0
(ii) A band-pass signal with bandwidth of 200
KHz if the lowest frequency is 100 KHz ?
3.
(a) Which characteristics of an analog sigmal are
changed to represent the digital signal in
each of the
following digital-to-analog
modulation?
(i) ASK
(ii) FSK
(i) PSK
(iv) QAM
(b) Why has the PCM sampling time been set at
125 Hsec?
2
(c) On which layer of the TCP/IP model does
the following devices operate. Briefly state
their functionality :
i) Repeater
(ii) Router
N
(ii) Bridges D
(iv Switches ND
P.T.O.
7405
4.
(a) Television channels
many
bits/sec can be sent if four-level digital
$1gnals
used ? Assume
are
channel.
24 mbps
(6) Explain briefly the
TDM.
(c) What
6 MHz wide. How
are
terms:
noiseless
3
a
FDM, WDM, and
3
is the
significance
twisted-pair cable?
of the
twisting
2
(d) What is the purpose
of cladding in
fiber?
5.
(a) Explain the binary
in
exponential
an
optical
2
back-off
algorithm used in CSMA/CD protocols.
(b
3
There are five classes in IPv4
addressing.
Give the identifiers for each of the
classes.
(c). Explain
3
the TCP header fields:
SYN, and FIN.
6.
(a) What
is HTTP ?
URG, PSH,
4
Explain briefly
message types.
(b) What is an URL ? Give an
its parts.
two of its
4
example to explain
3
(c) Briefly explain any three ICMP
message
types.
3
6
7405
7.
(a) Consider the following subnet where distance
vector routing is used. The
following
iniormation have just arrived at the router C :
4
(i) From B : (5,0,8,12,6,2)
(ii) From D : (16,12,6,0,9, 10) and,
(ii) From E: (7,6,3,9,0,4)
The measured
delays to B, D, and E, are 6,
and
3,
5 respectively. Give the new
routing
table for C
both
the
specifying
and the
delay
outgoing line to use
2
C
A
8
E
F
b) Compare ARP and RARP.
(c) What is MIME ? What
3
problems does it solve?
3
7
1300
This
question paper
contains 4+2
printed pages
Roll No.
S. No. of Question Paper
50
Unique Paper Code
32341303
Name of the
Computer Netw orks
Paper
Name of the Course
B.Sc. (Hons.) Computer Science
Semester
Duration :3 Hours
Maximum Marks: 75
(Hriteyour Roll No on the topimmwdiateh on receipt of this guestion ,uper
Question No. 1 is compulsory.
Attempt any four questions from Question Nos. 2 to
1.
(a)
Describe how piggybacking is used in the sliding window
protocol?
(b)
How is ARP different from RARP 3
(C)
Write the standard port numbers used by the follow ing
protocols
(
HTTP
(i)
TELNET
(ii)
FTP
() SMTP
P.TO
50
2
()
Let the data rate of 128 QAM signal be 14Kbps. Find
the maximum bandwidth required to transmit this
Signal.
(e)
Explain all the six tag bits used in the TCP segment
3
Header.
)
The following character encoding is used in a data link
3
protocol
A: 10110110: B 10101110: FLAG 0111110
ESC
11100000 show the bit sequence transmitted (in
binary) for the four character frame : A B ESC FLAG
when each of the following framing methods are used
()Charactercount.
(ii)
Flag bytes with byte stuffing,
(ii) Starting and
ending
flag
bytes,
with
bit
stuffing.
(g)
Describe various components of a URL.
(h)
Explain the TCP connection termination process.
()
Which layer(s) in the OSI model, performs the following
services ?
(i)
Process to Process Communication
(ii)
Synchronization
50
3)
(ii) Encryption and Decryption
(v)
Mail Services
(v)
Node to Node Communication
(vi) Acess Control.
Draw the pulse diagram for the bit stream 10011000011
using
the
following encoding techniques
(i)
Manchester encoding
(in)
Differential Manchester
encoding.
(iin) NRZ-1,
(k)
(v)
AM1
()
HDB3.
Distinguish
()
between the
Virtual Circuit
following
Switching
and
Datagram Packet
Switching
(i)
Non-Persistent CSMA and P-Persistent CSMA
(ii) Time Division Multiplexing
and
Frequency Division
Multiplexing.
P.T.O.
4
2
(u)
What is the
0
Binary Exponential Backoff algorithm
Ethernet ? How does it reduce the
probability
used in
of collision
in the Ethernet ?
(b)
Let
an
IPV4
datagrams
field values HLEN
Offset
4
is received with the
10. Total
Length
=
200.
following
Fragment
100, and MF I :
()
Find the
(i)
What is the size of the
Payload carried by
the
Datayram.
option
field in the
header ?
(iii)
What is the
starting
and end
byte
of the
payload
for the Datagram ?
(c)
()
What
are
the
periodic signals
4
and
why
are
they commonly
used in the analog transmission ?
3
(a)
Explain Distance Vector Routing.Algorithm. Also discuss
the Count to
(b)
2
Infinity problem.
4
The network 180.242.0.0/16 has been subdivided into /19
networks
6
How many /19 sub networks are there ? Give their
addresses.
(i)
How many hosts can be on each network ?
(iii) Determine which network the IP address
180.242.108.93 belongs to.
5)
4
(a)
50
How does the sliding window protocol handling flow
control in the network ? Explain using the Go Back N
4
protocol.
(6)
(b)
A receiver receives the vector 11110111001. Using the
Hamming code algorithm, find the original code that was
4
sent.
A digital signal with 8 levels needs to transmit on a
noiseless channel. Assuming the channel bandwidth is
100 kHz. Find the maximum data rate of the signal.
5
(a)
2
What is PPP protocol and its features ? Also give the
frame format of PPP.
(6)
Give a brief description of HTTP message headers and
their types.
(c)
Define DNS and give one example each of absolute
domain name and relative domain name.
6
(a)
List all the problems that are associated with Remote
4
Procedure Calls.
(b)
Explains all the fields of the IP header frame format with
the help of a diagram.
(c)
Assume that source S and destination D are connected
through three intermediate routers. Determine how many
times each packet has to visit the network and data link
layer during
transmission from S to
D.
P.T.O.
6
A channel has a bit rate of 8Kbps and a propagation
(a)
delay of 40 ms. For what range of frame sizes, Stop
and Wait protocol give an efficiency of at least
50 percent ?
Why do we necd a guard band in Frequency Division
(b)
Multiplexing
Write short notes on the following (do any three)
(c)
(
6
Www
(in
DHCP
(in) Guided Media
() UDP
50
6
,400
This
question
paper contains 3
printed pages
Roll No.
S. No. of Question Paper
2048
Unique Paper Code
:32341303
Name
:ComputerNetworks
of the Paper
Name of the Course
I
:B.Sc. (H)
GC-3
Computer Science (CBCS)
Semester
Duration:3 Hours
Maximum Marks: 75
(Write your Roll No. on the top immediately on receipt of this question paper.)
Part A is compulsory and carries 35 marks.
Attempt any four questions from Part B.
Part A
1.
(a)
Name and state the two types of line configuration.
(b)
Assume five devices
are
arranged in a
mesh
topology.
How many ports
are
needed for
each device ? How many cables are needed in this topology?
(c)
What is the difference between data element and signal element ?
(d)
What are the parts of a URL ? Give an example.
(e)
State optimality principle
What is the
(g)
use
of Urgent Pointer
What is the purpose of
options
in
a
field in
TCP header?
an
IP Header ?
Explain
any
two
options.
3
P.T.O.
2048
2
h)
State count
to
infinity problem.
Give
an
What is QAM ? Give the constellation
example.
diagram
4A
(a)
Desc
b)
Expi
(c)
Wh
for 64 QAM.
What is the purpose of using Guard Bands in multiplexed channels ?
(k)
What is the significance of twisting in twisted-pair cables ?
(
What is Discrete Multitone technique ?
(m)
What is flow control ? How is it handled at data link layer
(n)
(n)
Which layer in the OSI model perform the following services
WH
(a)
W
3
(b)
A
3
(c)
()
Translation
(ii)
Network virtual terminal
6
(iii)
(a)
Synchronization.
Part B
2.
2
3.
3
(a)
Explain layered OSI model, stating the functionality of each layer.
5
(b)
Explain the concept of self-synchronization in reference to digital signals.
2
(c)
Explain
the basic difference between
(a)
What is
subnetting ?
A network
What is the maximum number
Give the
(c)
Why is header checksum of
destination?
hub, bridge and
the internet has
of hosts
it
can
a
a
3
switch.
subnet
mass
of 255.255.240.0.
(C
handle?
of TCP Header. Discuss the purpose of six one-bit
(b)
structure
on
a
an
IP
packet computed
(b)
at every
hop
flags.
from
2+3
source to
2048
2048
3)
4.
2048
(a)
Describe the binary
(6)
Explain the multimode technique used for propagation of light in optical fibres.
(c)
What
(a)
What is the Nyquist sampling rate for a bandpass signal with bandwidth of 300 ktlz
are
back off algorithnm.
the differences between
with lowest
(b)
exponential
frequency
as
Packet
switching
and circuit
switching?
100 kHz.
2
A bit string needs to be transmitted at the data link layer. What is the string transmitted
after bit stufiing ifthe original bit string is 0111101111101111110.
(c)
Explain the two basic approaches that use the concept of pipelining at data link
layer
6.
6
What is the result ofapplying the following schemes on sequence 11100000000000 ?
(a)
Assume that before arrival of this signal, the non-zero signal level has been positive. 4
5
(b)
()
B8ZS
(i)
HDB3
16 bit messages are transmitted using a hamming code. How many check bits are needed
to ensure that the receiver can detect and correct single bit errors ? Show the bit pattern
3
transmitted for the message 1101001100110101.
0.
3
(c)
2048
Write a short note on any one of the following
()
www
(i)
DNS.
3
2
800