CN Final exam Nov 2023_Phoenix

Examination Information

  • Program: bac Computing and Information Systems PROGRAMMES: BSC BSC

  • Course Code: MT202-Computer Networks

  • Final Examination Date: 8th November 2023

  • Time: 11:00

  • Total Marks: 100

  • Duration: 2 hours 30 minutes

Instructions to Candidates

  1. Candidates must attempt ANY four (4) questions.

  2. Attempting to gain unfair advantage or colluding will lead to disqualification.

  3. Do NOT open the question paper until instructed.

  4. Do not bring materials for copying, colluding, or plagiarizing.

  5. No writing on the question paper; all rough work must be indicated at the end of the answer booklet.

Page Overview

  • The question paper consists of 8 pages including cover pages.

Question 1: Variable Length Subnet Masking (VLSM)

a) Design Requirements

  • Network Address: 192.168.24.0/24

  • Departments and Hosts:

    • Net 1: 120 hosts

    • Net 2: 62 hosts

    • Net 3: 14 hosts

    • Net 4: 2 hosts

Questions

  1. Class of IP Address:

    • Answer: Class C (for address 192.168.24.0)

  2. Fixed Length Subnet Mask:

    • Answer: 255.255.255.128 (for 128 available hosts)

  3. Disadvantages of Fixed Length Mask:

    • Inefficient allocation of IP addresses.

    • Wasted IP addresses in subnets with fewer hosts.

  4. Implementing VLSM:

    • Subnet Mask (for each subnet):

      • Net 1: 255.255.255.0 (or /24)

      • Net 2: 255.255.255.192 (or /26)

      • Net 3: 255.255.255.240 (or /28)

      • Net 4: 255.255.255.252 (or /30)

    • Network Addresses:

      • Net 1: 192.168.24.0

      • Net 2: 192.168.24.128

      • Net 3: 192.168.24.192

      • Net 4: 192.168.24.240

    • Broadcast Addresses:

      • Net 1: 192.168.24.255

      • Net 2: 192.168.24.191

      • Net 3: 192.168.24.207

      • Net 4: 192.168.24.243

    • Range of Usable IPs:

      • Net 1: 192.168.24.1 - 192.168.24.254

      • Net 2: 192.168.24.129 - 192.168.24.190

      • Net 3: 192.168.24.193 - 192.168.24.206

      • Net 4: 192.168.24.241 - 192.168.24.242

b) Using AND Operation

  • IP Address: 172.16.10.23

  • Subnet Mask: 255.255.248.0

  • Complete calculation for network address using AND operation.

c) IPv6 Address Compression

  • Uncompressed IPv6 Address: 2001:0000:0000:0080:0000:0000:0000:0A00

  • Compressed Format: 2001:0:0:80:0:0:0:A00

Question 2: Cisco IOS Commands

Cisco IOS Commands Required

  1. Disable DNS lookup:

    • Command: no ip domain-lookup

  2. Change router name to R1:

    • Command: hostname R1

  3. Configure Encrypted Privileged Exec Password:

    • Command: enable secret [password]

  4. Configure Console Access Password:

    • Command: line con 0; password [password]; login

  5. Configure Telnet Access Password:

    • Command: line vty 0 4; password [password]; login

Command Functions on Cisco Router

  1. Enable:

    • Activates privileged EXEC mode.

  2. Configure terminal:

    • Access global configuration mode.

  3. service password-encryption:

    • Encrypts plaintext passwords.

  4. ipconfig (Windows):

    • Displays network configuration details.

  5. banner motd:

    • Sets a Message of the Day for users at login.

Explanation of Configuration Actions:

  • Tab/Space bar: Scroll through the running configuration.

  • ?: Helps with command completion.

  • Up arrow: Recalls the last command.

  • Ctrl-Z: Exits configuration mode.

Question 3: Networking Concepts

Client/Server vs Peer-to-Peer Network

Client/Server Network

  • Advantages:

    1. Centralized control.

    2. Easier to manage security.

  • Disadvantages:

    1. Higher cost for setup.

    2. Single point of failure.

Peer-to-Peer Network

  • Advantages:

    1. Lower cost.

    2. No central management needed.

  • Disadvantages:

    1. Security challenges.

    2. Difficult backup management.

Network Term Functions

  1. Router: Directs data between networks.

  2. Firewall: Monitors and filters incoming/outgoing traffic.

  3. DSL Modem: Connects to internet via telephone line.

Definitions

Network Terms

  1. Internet: Global interconnected network.

  2. Intranet: Private network within an organization.

  3. Extranet: Controlled private network extending to customers/suppliers.

Communication Terms

  1. Broadcast: Transmits to all devices in a network.

  2. Multicast: Transmits to selected devices.

  3. Unicast: One-to-one communication.

  4. Anycast: One-to-nearest communication.

Cloud Computing

  • Concept: Remote service access via internet to store and manage data.

  • Advantages: Accessibility from anywhere.

  • Disadvantages: Security and dependency on internet access.

Question 4: Network Management

a) Remote Management IP Configuration

  • Interface for Configuring: Management interface (typically VLAN interface).

b) PDU Formats by Layers

  1. Application Layer: Data

  2. Transport Layer: Segments

  3. Network Layer: Packets

  4. Data Link Layer: Frames

  5. Physical Layer: Bits

c) Frame Handling in Ethernet Networks

  • Action on Unknown MAC: Flood the frame to all ports except the source port until the MAC address is learned.

d) Fiber Optic vs Copper Cabling

  • Comparison:

    • Fiber Optic Advantages:

      1. Longer distance transmission.

      2. Higher bandwidth.

    • Copper Advantages:

      1. Lower cost.

      2. Simpler installation.

e) Contention-Based Methods

  1. CSMA/CD (Carrier Sense Multiple Access with Collision Detection): Wired communication.

  2. CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance): Wireless communication.

f) Ethernet Frame Reception Behavior

  • Action for Unmatched MAC: Discard the frame.

g) Address Resolution Protocol (ARP)

  • Role of ARP: Maps IP addresses to corresponding MAC addresses in a network.

Question 5: Networking Cable Types

a) Cable Type for Connections

  • Cable Types:

    • Device connections (1, 2, 3): determine type (straight-through, crossover, or rollover).

b) Coaxial Cable Structure Roles

  1. Copper Conductor: Carries the signal.

  2. Braided Copper Shielding: Protects against external interference.

c) Twisted Pair Cables

  1. Reason for Twisting: Minimizes electromagnetic interference.

  2. Performance of STP over UTP: Better protection against interference.

d) Device Naming Importance

  • Importance of Hostnames: Simplifies device identification and management.

e) Broadcast Domain Issues

  • Problem: Increased traffic and potential collisions in large domains.

f) OSI Layer for MAC Addresses

  • Layer: Data Link Layer (Layer 2).

g) Differences in Fiber Cable Types

  • Single Mode vs Multimode:

    • Single Mode: Longer distance, cost higher.

    • Multimode: Shorter distances, less expensive.

h) Protocols in OSI Layers

  1. Data Link Layer Protocol Example: Ethernet.

  2. Internet Layer Protocol Example: IP (Internet Protocol).

i) Communication Types

  • Half vs Full Duplex: Half is one-direction at a time, full is two-direction simultaneously.

j) Network End Devices

  • Examples: Computer, Switch, Router.

k) IPv4 to IPv6 Replacement Reason

  • Main Reason: Address exhaustion in IPv4.