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CMN620S - COMMUNICATION NETWORKS - 2ND OPP - JAN 2025 |
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nAmlBIA UnlVERSITY
OF SCIEnCE Ano TECHnOLOGY
Faculty of Computing and Informatics
Department of Computer Science
QUALIFICATION:BACHELOR OF COMPUTER SCIENCEIN CYBERSECURITY
BACHELOR OF COMPTER SCIENCE
QUALIFICATIONCODE: 07BCCS; 07BCMS
LEVEL: 7
COURSE:COMMUNICATION NETWORKS
COURSECODE: CMN620S
DATE:JANUARY 2025
SESSION: PAPER 2
DURATION: 2 HOURS 30 MINUTES
MARKS: 80
SECONDOPPORTUNITY/ SUPPLEMENTARYEXAMINATION QUESTION PAPER
EXAMINER{S}
MR. NASIMANE EKANDJO
MS. LOINI IIYAMBO
MS. HELENA HAINANA
MR. BEN MWASHEl<UNA
MR. SHOOPALA NAMBAHU
MS. TALENI ANDJAMBA
MS. ADELHEID GEINGOS
MODERATOR:
MR. EDWARD NEPOLO
THIS QUESTION PAPERCONSISTSOF 7 PAGES
(Excluding this front page)
INSTRUCTIONS
1. Answer ALL the questions.
2. Write clearly and neatly.
3. Number the answers clearly.
4. When answering questions you should be guided by the allocation of
marks. Do not give too few or too many facts in your answers.
PERMISSIBLEMATERIALS
1. Non-programmable calculator.
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Question 1
For the following questions, answer True/False.
[5]
1.1 The default VLAN in most switches in VALN 1.
1.2 In an enterprise access network (Ethernet), transmission rates ranges from 10 Mbps, 100
Mbps, 1 Gbps to 10 Gbps.
1.3 Intra-AS routing makes use of Exterior Gateway Protocol (EGP).
1.4 An IP address 200.70.70.1 can only be used outside a LAN because it is a public IP address.
1.5 When utilising a cable network or DSLaccess network, the upstream transmission rate is
higher than the downstream transmission rate.
Question 2
Choose the correct answer from the multiple choice questions below.
[5]
2.1 What protocol is commonly used for VLAN tagging in Ethernet frames?
a) ARP
b) PPP
c) 802.lQ
d) ICMP
2.2 An Ethernet cable that is made up by having one end of 568A standard and the other end
of568Bisa/an __ _
a) Crossover cable
b) Rollover cable
c) Straightthrough cable
d) Serial cable
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2.3 After how long can a router wait to hear from its neighbor in order for it to consider that its
neighbor is no longer reachable?
a) 30 seconds
b) 3 minutes
c) 30 minutes
d) No limit of waiting time
2.4 Which of the following will be needed by a PC in order to send a packet to a destination
outside its own subnet?
a) VLAN
b) ARP
c) Default gateway
d) Switch
2.5 Which two DHCPpacket types contain an IP address to be leased to a client?
a) Offer and Release
b) Offer and NAI<
c) Offer and Acknowledgement
d} Offer and Renew
e) None of the above
Question 3
3.1 In a network that is configured with OSPFas a routing protocol, what are the benefits of
dividing that network into areas?
[2]
3.2 What is the role of a designated router (DR)?
[2]
3.3 Explain the process of electing a DR and a Backup DR.
[3]
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Question 4
4.1 Explain two disadvantages of twisted pair cable.
[2]
4.2 What is the difference between multi-mode and single-mode fiber-optic cable?
[2]
Question 5
5.1 What is DSLaccess network and how does it work?
[3]
5.2 In what way is the enterprise accessnetwork (ethernet) different from DSLaccess network?
[2]
5.3 Name any two network access type other than the two mentioned above.
[2]
Question 6
6.1 Outline three benefits of utilizing VLANs in a network?
[3]
6.2 Consider the topology below and answer the questions that will follow.
,..._. ________
rtI
PC.PT
Rhoman
VLAN7
Management
.~~"
PC-PT
Tresor
VLAN 70
[T
rtJ
PC-PT
Celine
VLAN 700
HR
Henry
VLAN 70
[T
a) What is the specific name of the ports that links the two switches together?
[2]
b) What is the specific name of the port that links S_l to Celine PC?
[1]
c) How many subnets can be created on VLAN 700?
[1]
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6.3
Below is an extract of S_l after the command show vlan was issued.
S_lilsh vlan
VLAN Name
Status
Ports
l
default
7 Management
70 IT
1002
1003
1004
1005
fddi-default
token-ring-default
fddinet-default
trnet-default
VLANT~•pe
l
7
70
1002
1003
1004
1005
enet
enet
enet
fddi
tr
fdnet
trnet
SAID
MTU
----------
100001
1500
100007
1500
100070
1500
101002
1500
101003
1500
101004
1500
101005
1500
Parent
-
-
-
active
active
active
active
active
active
active
Fa0/2,
FaO/€,
Fa0/24,
Fa0/7,
Fa0/11,
FaO/lS
Fa0/1€,
Fa0/20
Fa0/3, Fa0/4, FalJ/S
Fa0/21, Fa0/22, Fa0/23
Gig0/1, Gig0/2
Fa0/8, Fa0/9, Fa0/10
Fa0/12, Fa0/13, Fa0/14
Fa0/17, Fa0/18, Fa0/19
RingNo BridgeNo Stp BrdgMode Transl
--------
--------
0
0
0
0
0
ieee -
0
- ibm
0
Trans2
0
0
0
0
0
0
0
How many VLANs have been created on the switch?
[1]
Question 7
Consider the network topology below and answer the questions that follow:
Public Network
Public Network
Cloud-PT
Internet
13.1.1.1 /30
192.168.1.1 /24
Private Network
Private Network
2960 24TT
Swi ch1
~u·
PC-PT
PC0
192.168.2.2 /24
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192.168.1.2 /24
L•-/=u 1
PC-PT
PC1
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7.1 From the above network topology, indicate which device interface (IP address) belong to:
a) Inside local: -----------
[1)
b)
Inside global: __________
_
[1)
c) Outside local: -----------
[1)
d) Outside global: __________
_
[1)
7.2 Explain two purposes of configuring Network Address Translation (NAT) on a network. [2)
7.3 Explain any two methods that can be used to implement NAT.
[4)
Question8
Consider the figure below and answer the questions that follow:
192.168.44.0 /24
2911
RouterO
177.77.77.0 /24
2911
RoutGr1
200.10.123.0 /24
LAN
L--/..J
PC-PT
PCO
8.1 Write down the full commands that will configure a static route on Router! so that the
router can direct traffic to their destinations. Assume the IP address of Router0's interface
leading to Router! is 177.77.77.1, while the IP address of Routerl's interface leading to
Roouter0 is 177.77.77.2.
[2)
8.2 On Router0, configure a standard access list using an access list of id 10 and permit any
device on the subnet 192.168.44.0 /24.
[3)
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8.3 PCl and PC2are required to obtain their IP addresses dynamically from router RouterO.This
router therefore needs to be configured with DHCPservices.
Consider the table below and write down the commands needed to configure a DHCPon
RouterO.
[3]
DHCP Pool Name Starting IP Address Ending IP Address Network Mask
CMN_EXAM
192.168.44.1
192.168.44.254
/ 24
8.4 Write down the command that will exclude IP addresses: 192.168.44.1 to 192.168.44.10
from being leased to the hosts on the LAN.
[2]
Question 9
Consider the following network topology and answer the questions that will follow.
Zimb bwe
LAN 1: 2000 Users
~,I)·
PC-PT
Aina
TT
3
L...:.-...:1".
PC-PT
EMs
LAN 3: 500 Users
j 11
'"1;1 I WAN_l
I
2960 24TT
Swil h_S
... f,_;·
PC-PT
Tsepo
LAN_S: 16 Users
\\
2 11
Za bia
LAN 2: 1100 Users
TT
sw· h_2
,,:;;f
sw· h_4
0~. 1
-.IJ.J
PC-PT
Tangeni
LAN 4: 60 Users
L--..ILJ.
PC-PT
Richard
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Execute the following requirements:
You have been allocated the class B IP address block 172.28.0.0 /19.
9.1 Subnet this IP address block to provide valid IP addresses to all users in the five LANs.You
are also required to provide valid IP addresses to the WAN links between the routers.
Re-draw the table below and fill it in:
[20]
LAN/WAN
LAN 1:
LAN 2:
LAN 3:
LAN 4:
LAN 5:
WAN 1
WAN 2
WAN3
Network Number
Subnet Mask (/)
Marks distribution: [1.5 marks for each network number]
[1 mark for each subnet mask]
Total= 20 marks
9.2 The recommended IP address for Aina PC is the last IP address of that subnet. Write down
this IP address.
[1]
Elvis: -----------
9.3 The recommended IP address for Tanzania router's interface leading to LAN 5 is the first IP
address of that subnet. Write down this IP address.
[1]
Tanzania: __________
_
9.4 Assume that the routing protocol configured in this network is RIP.From the networks listed
below, choose any two networks that will be learned by Tanzania router.
[2]
LAN 1; LAN 2; LAN 3; LAN 4; LAN 5 WAN 1; WAN 2; WAN 3
End of Paper
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