Question 1(a) [3 marks]#
What is the Computer Network? Why it is important?
Answer: A computer network is a collection of interconnected computing devices that can exchange data and share resources.
Diagram:
- Resource sharing: Enables sharing of printers, files, applications
- Communication: Facilitates information exchange between users
- Scalability: Allows networks to grow as needs increase
Mnemonic: “CSI” - “Connect, Share, Interact”
Question 1(b) [4 marks]#
Define terms: 1) Web Server, 2)Encrypted data, 3)Hacking, 4)Client-server
Answer:
| Term | Definition |
|---|---|
| Web Server | Software/hardware that serves web content to clients using HTTP/HTTPS |
| Encrypted Data | Information converted to code to prevent unauthorized access |
| Hacking | Unauthorized access to computer systems through security vulnerabilities |
| Client-Server | Network model where centralized servers provide services to client computers |
Diagram:
Mnemonic: “WECHS” - “Web servers Encrypt data, Clients and Hackers use Servers”
Question 1(c) [7 marks]#
Classify and explain the transmission media in detail.
Answer: Transmission media are physical pathways that carry data in a network.
| Category | Types | Characteristics | Applications |
|---|---|---|---|
| Guided Media | |||
| Twisted Pair | UTP, STP | 100m range, 10Mbps-10Gbps | Office LANs |
| Coaxial Cable | Baseband, Broadband | 500m range, 10-100Mbps | Cable TV, Internet |
| Fiber Optic | Single-mode, Multi-mode | Long distance, 100Mbps-100Gbps | Backbone, WAN |
| Unguided Media | |||
| Radio Waves | WiFi, Cellular | Omnidirectional, 1-100Mbps | Wireless networks |
| Microwaves | Terrestrial, Satellite | Line-of-sight, 1-10Gbps | Point-to-point links |
| Infrared | IrDA | Short-range, 4-16Mbps | Remote controls |
Diagram:
- Guided media: Physical paths for signal confinement
- Unguided media: Wireless transmission through air/space
- Selection factors: Cost, bandwidth, distance, environment
Mnemonic: “TCFRIM” - “Twisted pair, Coaxial, Fiber, Radio, Infrared, Microwave”
Question 1(c) OR [7 marks]#
Explain WAN and MAN type of network.
Answer: Wide Area Networks (WAN) and Metropolitan Area Networks (MAN) are network types classified by geographic scope.
| Feature | MAN (Metropolitan Area Network) | WAN (Wide Area Network) |
|---|---|---|
| Coverage | City-wide (5-50 km) | Country/Global (>50 km) |
| Speed | 10 Mbps - 10 Gbps | 1.5 Mbps - 1 Gbps |
| Ownership | Municipal/Telecom | Multiple organizations |
| Technologies | Ethernet, SONET, WiMAX | Frame Relay, ATM, MPLS |
| Examples | City networks, Campus networks | Internet, Corporate networks |
Diagram:
- MAN: Connects LANs within a city/metropolitan area
- WAN: Spans large geographical areas across cities/countries
- Management: WAN typically requires service providers
- Infrastructure: Different transmission media and technologies
Mnemonic: “SWIM” - “Size: WAN Is Massive compared to MAN”
Question 2(a) [3 marks]#
Explain in detail: Transmission technology.
Answer: Transmission technology refers to methods used to transfer data between network devices.
| Technology Type | Description | Example |
|---|---|---|
| Point-to-Point | Direct connection between two nodes | Leased line |
| Broadcast | Single communication channel shared by all nodes | Wireless LAN |
| Multipoint | Multiple devices share single link | Cable networks |
- Analog transmission: Continuous signal, susceptible to noise
- Digital transmission: Discrete signal, more reliable
- Baseband: Single signal uses entire bandwidth (Ethernet)
- Broadband: Multiple signals share bandwidth (Cable TV)
Mnemonic: “ABP-DMB” - “Analog or Baseband, Point-to-point; Digital or Multipoint, Broadcast”
Question 2(b) [4 marks]#
Draw and explain Star topology in detail.
Answer: Star topology is a network configuration where all devices connect to a central hub/switch.
Diagram:
| Advantages | Disadvantages |
|---|---|
| Easy installation | Single point of failure (hub/switch) |
| Simple troubleshooting | Requires more cable than bus topology |
| Scalable | Higher cost due to central device |
| Better performance | Hub/switch limits determine network size |
- Operation: All data passes through central device
- Installation: Easier to manage and expand
- Fault isolation: Node failure doesn’t affect others
Mnemonic: “CASE” - “Centralized, All connected, Simple expansion, Easy troubleshooting”
Question 2(c) [7 marks]#
Draw and explain TCP/IP model.
Answer: TCP/IP model is a conceptual framework used for network communications, consisting of four layers.
Diagram:
| Layer | Main Functions | Protocols |
|---|---|---|
| Application | User interfaces, data formatting | HTTP, FTP, SMTP, DNS |
| Transport | End-to-end communication, reliability | TCP, UDP |
| Internet | Logical addressing, routing | IP, ICMP, ARP, IGMP |
| Network Access | Physical addressing, media access | Ethernet, WiFi, PPP |
- Application Layer: Interface between applications and network
- Transport Layer: Reliable data transfer between end systems
- Internet Layer: Routing packets across networks
- Network Access Layer: Physical connection to network media
Mnemonic: “ATNI” - “Application Talks, Network Internet Interfaces”
Question 2(a) OR [3 marks]#
Draw and explain Bus topology in detail
Answer: Bus topology is a network configuration where all devices connect to a single communication line.
Diagram:
| Advantages | Disadvantages |
|---|---|
| Simple layout | Single point of failure (main cable) |
| Less cabling | Limited cable length |
| Low cost | Performance degrades with more nodes |
| Easy to extend | Difficult to troubleshoot |
- Operation: Data travels along the bus in both directions
- Terminator: Required at both ends to prevent signal reflection
- Usage: Primarily in older networks, small setups
Mnemonic: “SLUE” - “Simple Layout, Uses less cable, Easy installation”
Question 2(b) OR [4 marks]#
Explain Network Classification based on its architecture.
Answer: Networks can be classified based on their architectural models that define how devices interact.
| Architecture | Characteristics | Example |
|---|---|---|
| Peer-to-Peer | Equal privileges, no dedicated servers | Home networks, small workgroups |
| Client-Server | Centralized services, dedicated servers | Enterprise networks, web services |
| Three-Tier | Presentation, application, and data tiers | Modern web applications |
| N-Tier | Multiple specialized tiers | Large distributed systems |
Diagram:
- Peer-to-Peer: Direct device communication, distributed resources
- Client-Server: Centralized resource management, better security
- Hybrid: Combines elements of both architectures
Mnemonic: “PCAN” - “Peer-to-peer, Client-server, Architecture Networks”
Question 2(c) OR [7 marks]#
Explain classification of IP address.
Answer: IP addresses are classified into different categories based on their structure and purpose.
| IP Classification | Range | Default Mask | Available Networks | Hosts/Network |
|---|---|---|---|---|
| Class A | 1.0.0.0 - 127.255.255.255 | 255.0.0.0 (/8) | 126 | 16,777,214 |
| Class B | 128.0.0.0 - 191.255.255.255 | 255.255.0.0 (/16) | 16,384 | 65,534 |
| Class C | 192.0.0.0 - 223.255.255.255 | 255.255.255.0 (/24) | 2,097,152 | 254 |
| Class D (Multicast) | 224.0.0.0 - 239.255.255.255 | N/A | N/A | N/A |
| Class E (Reserved) | 240.0.0.0 - 255.255.255.255 | N/A | N/A | N/A |
Special IP Ranges:
- Private IPs: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
- Loopback: 127.0.0.0/8 (typically 127.0.0.1)
- Link-local: 169.254.0.0/16
Diagram:
- Classful addressing: Original IP address classification scheme
- CIDR (Classless): Modern approach that allows flexible subnet masks
- IPv4 vs IPv6: IPv4 uses 32-bit addresses, IPv6 uses 128-bit addresses
Mnemonic: “ABCDE” - “Address Blocks Categorized by Decreasing End-host counts”
Question 3(a) [3 marks]#
What is full name of LAN? Explain it in detail.
Answer: LAN stands for Local Area Network, a network confined to a limited geographic area.
Diagram:
| LAN Characteristics | Description |
|---|---|
| Geographic Scope | Building, campus, or small area (1-2 km) |
| Data Rate | High (10 Mbps to 10 Gbps) |
| Ownership | Single organization or individual |
| Technology | Ethernet, WiFi, Token Ring |
| Media | Twisted pair, fiber optic, wireless |
- Purpose: Connect nearby devices for resource sharing
- Administration: Easier management than larger networks
- Applications: Office networking, home networking
Mnemonic: “LOCAL” - “Limited in range, Owned by one entity, Connected devices, Access control, Low latency”
Question 3(b) [4 marks]#
Write a short-note of Repeater.
Answer: A repeater is a network device that amplifies and regenerates signals to extend network range.
Diagram:
| Feature | Description |
|---|---|
| OSI Layer | Physical Layer (Layer 1) |
| Function | Signal regeneration and amplification |
| Purpose | Extend network transmission distance |
| Limitation | Cannot filter traffic or connect different networks |
- Operation: Receives, regenerates, and retransmits signals
- Usage: Extending cable length beyond normal limits
- Types: Traditional repeaters, hubs (multiport repeaters)
Mnemonic: “RARE” - “Repeaters Amplify and Regenerate Electrical signals”
Question 3(c) [7 marks]#
Write short note on FTP.
Answer: File Transfer Protocol (FTP) is a standard network protocol for transferring files between clients and servers.
Diagram:
| Feature | Description |
|---|---|
| Port | Control: 21, Data: 20 |
| Mode | Active or Passive |
| Authentication | Username/password (or anonymous) |
| Transfer Types | ASCII (text) or Binary (raw data) |
| Security | Basic FTP (unsecured), FTPS, SFTP (secure variants) |
- Dual Channel: Separate control and data connections
- Commands: GET, PUT, LIST, DELETE, RENAME, etc.
- User Authentication: Requires login credentials
Mnemonic: “CDATA” - “Control channel, Data channel, Active/passive modes, Transfer types, Authentication”
Question 3(a) OR [3 marks]#
What is full name of PAN? Explain in detail.
Answer: PAN stands for Personal Area Network, a network for connecting devices centered around an individual.
Diagram:
| PAN Characteristics | Description |
|---|---|
| Geographic Scope | Very small (1-10 meters) |
| Data Rate | Low to medium (100 Kbps - 100 Mbps) |
| Ownership | Individual person |
| Technology | Bluetooth, Zigbee, NFC, Infrared |
| Devices | Personal devices (phones, wearables, laptops) |
- Purpose: Connect personal devices for communication/data sharing
- Types: Wired PAN (USB) and Wireless PAN (Bluetooth)
- Applications: Data synchronization, audio streaming, health monitoring
Mnemonic: “PIPER” - “Personal, Individual, Proximity, Easy setup, Reduced range”
Question 3(b) OR [4 marks]#
What is the importance of a Bridge? Write short-note on it.
Answer: A bridge is a network device that connects and filters traffic between network segments.
Diagram:
| Feature | Description |
|---|---|
| OSI Layer | Data Link Layer (Layer 2) |
| Function | Connect similar network segments |
| Intelligence | Uses MAC addresses to filter traffic |
| Advantage | Reduces unnecessary traffic between segments |
- Importance: Extends network, reduces collision domains
- Operation: Learns MAC addresses, forwards frames selectively
- Types: Transparent, translational, source-route bridges
Mnemonic: “SELF” - “Segmentation, Extension, Learning addresses, Filtering traffic”
Question 3(c) OR [7 marks]#
What is DSL? Explain its different types.
Answer: Digital Subscriber Line (DSL) is a family of technologies that provides digital data transmission over telephone lines.
Diagram:
| DSL Type | Full Name | Speed (Down/Up) | Distance | Application |
|---|---|---|---|---|
| ADSL | Asymmetric DSL | 8 Mbps/1 Mbps | Up to 5.5 km | Residential internet |
| SDSL | Symmetric DSL | 2 Mbps/2 Mbps | Up to 3 km | Small business |
| VDSL | Very high-bit-rate DSL | 52-85 Mbps/16-85 Mbps | Up to 1.2 km | Video streaming, businesses |
| HDSL | High-bit-rate DSL | 2 Mbps/2 Mbps | Up to 3.6 km | T1/E1 replacement |
| IDSL | ISDN DSL | 144 Kbps/144 Kbps | Up to 5.5 km | ISDN alternative |
- Working Principle: Uses unused frequency spectrum on phone lines
- Advantage: Uses existing telephone infrastructure
- Always-on: Continuous connection without dial-up
Mnemonic: “SAVHI” - “Symmetric, Asymmetric, Very high-bit-rate, High-bit-rate, ISDN DSL”
Question 4(a) [3 marks]#
Explain an error control and flow control at data link layer.
Answer: Error and flow control are essential data link layer functions that ensure reliable data transmission.
| Mechanism | Purpose | Techniques |
|---|---|---|
| Error Control | Detect/correct transmission errors | CRC, Checksums, Parity bits |
| Flow Control | Prevent sender overwhelming receiver | Stop-and-wait, Sliding window |
Diagram:
- Error Detection: CRC, checksum identify corrupted frames
- Error Correction: Forward Error Correction (FEC), retransmission
- Flow Control: Prevents buffer overflow at receiver
Mnemonic: “SAFE” - “Stop-and-wait, Acknowledgment, Flow control, Error detection”
Question 4(b) [4 marks]#
What is Firewall? Explain it in detail.
Answer: A firewall is a network security device that monitors and filters incoming and outgoing network traffic.
Diagram:
| Firewall Type | Functionality | Example |
|---|---|---|
| Packet Filtering | Examines packet headers | Router ACLs |
| Stateful Inspection | Tracks connection state | Most hardware firewalls |
| Application Layer | Inspects content | Web application firewalls |
| Next-Generation | Combines multiple technologies | Palo Alto, Fortinet |
- Purpose: Protects networks from unauthorized access
- Implementation: Hardware, software, or cloud-based
- Security Policy: Rules defining allowed/blocked traffic
Mnemonic: “PAPSI” - “Packet filtering, Application layer, Policies, Stateful inspection”
Question 4(c) [7 marks]#
Compare IPV4 and IPV6.
Answer: IPv4 and IPv6 are Internet Protocol versions with significant differences in addressing and capabilities.
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address Size | 32-bit (4 bytes) | 128-bit (16 bytes) |
| Format | Dotted decimal (192.168.1.1) | Hexadecimal with colons (2001:0db8:85a3::8a2e:0370:7334) |
| Address Space | ~4.3 billion addresses | 340 undecillion addresses |
| Header | Variable length (20-60 bytes) | Fixed length (40 bytes) |
| Fragmentation | Routers and sending hosts | Only sending hosts |
| Checksum | Included in header | Removed from header |
| Security | Not built-in (IPsec optional) | Built-in IPsec support |
Diagram:
- Auto-configuration: IPv6 has stateless address auto-configuration
- NAT: Not required in IPv6 due to larger address space
- Transition: Dual-stack, tunneling, translation mechanisms
- Header efficiency: IPv6 has streamlined header for better performance
Mnemonic: “SHAPE” - “Size, Header, Addressing, Performance, Extensibility”
Question 4(a) OR [3 marks]#
What is an IP address? How it is used in network?
Answer: An IP address is a numerical identifier assigned to each device connected to a network that uses Internet Protocol.
Diagram:
| IP Address Usage | Description |
|---|---|
| Identification | Uniquely identifies devices on a network |
| Routing | Determines path for data packets |
| Addressing | Enables sending data to specific destinations |
| Network Division | Allows subdivision into subnets |
- Structure: Network portion and host portion
- Assignment: Static (manual) or dynamic (DHCP)
- Versions: IPv4 (32-bit) and IPv6 (128-bit)
Mnemonic: “IRAN” - “Identification, Routing, Addressing, Network division”
Question 4(b) OR [4 marks]#
Compare FDDI and CDDI.
Answer: FDDI (Fiber Distributed Data Interface) and CDDI (Copper Distributed Data Interface) are high-speed network technologies.
| Feature | FDDI | CDDI |
|---|---|---|
| Medium | Fiber optic cable | Copper twisted pair |
| Speed | 100 Mbps | 100 Mbps |
| Distance | Up to 200 km total, 2 km between stations | Up to 100 m between stations |
| Topology | Dual counter-rotating rings | Dual counter-rotating rings |
| Cost | Higher | Lower |
| Reliability | Very high | Moderate |
| Standard | ANSI X3T9.5 | Same as FDDI (adapted for copper) |
Diagram:
- Redundancy: Secondary ring for fault tolerance
- Access Method: Token passing with timed token rotation
- Applications: FDDI for backbones, CDDI for workstations
Mnemonic: “FDDI Flies, CDDI Crawls” - Fiber for long distance, Copper for shorter runs
Question 4(c) OR [7 marks]#
Draw and explain OSI reference model in detail.
Answer: The OSI (Open Systems Interconnection) model is a conceptual framework that standardizes network functions into seven layers.
Diagram:
| Layer | Primary Function | Protocols/Standards | Data Unit |
|---|---|---|---|
| Application | User interface, network services | HTTP, FTP, SMTP | Data |
| Presentation | Data formatting, encryption | SSL/TLS, JPEG, MIME | Data |
| Session | Connection establishment, management | NetBIOS, RPC | Data |
| Transport | End-to-end delivery, flow control | TCP, UDP | Segments |
| Network | Logical addressing, routing | IP, ICMP, OSPF | Packets |
| Data Link | Physical addressing, media access | Ethernet, PPP, HDLC | Frames |
| Physical | Bit transmission, cabling, signaling | USB, Ethernet, Bluetooth | Bits |
- Layer Independence: Each layer performs specific functions
- Encapsulation: Data wrapped with headers at each layer
- Standardization: Promotes interoperability between systems
- Troubleshooting: Isolates problems to specific layers
Mnemonic: “All People Seem To Need Data Processing” (Layers 7 to 1)
Question 5(a) [3 marks]#
What is ISO? How it works in information security?
Answer: ISO (International Organization for Standardization) develops and publishes standards including those for information security.
| ISO Security Standards | Purpose |
|---|---|
| ISO/IEC 27001 | Information security management systems |
| ISO/IEC 27002 | Code of practice for security controls |
| ISO/IEC 27005 | Information security risk management |
| ISO/IEC 27017 | Cloud security |
| ISO/IEC 27018 | Protection of personally identifiable information |
Working in Information Security:
- Framework-based: Provides structured approach to security
- Risk-based: Focuses on identification and mitigation of risks
- Process-oriented: Establishes continuous improvement cycle
- Certification: Organizations can be certified for compliance
Mnemonic: “PRIMP” - “Policies, Risk assessment, Implementation, Monitoring, Process improvement”
Question 5(b) [4 marks]#
Explain terms in detail for cryptography: 1) Encryption 2) Decryption
Answer: Encryption and decryption are fundamental processes in cryptography that secure information.
| Term | Definition | Types | Example Algorithms |
|---|---|---|---|
| Encryption | Process of converting plaintext to ciphertext using an algorithm and key | Symmetric, Asymmetric, Hybrid | AES, RSA, ECC |
| Decryption | Process of converting ciphertext back to plaintext using an algorithm and key | Symmetric, Asymmetric, Hybrid | AES, RSA, ECC |
Diagram:
Encryption:
- Purpose: Protects confidentiality of information
- Methods: Substitution, transposition, block cipher, stream cipher
- Key Management: Critical aspect of secure encryption
Decryption:
- Purpose: Retrieves original information from encrypted form
- Requirements: Correct algorithm and key
- Implementation: Hardware or software-based
Mnemonic: “PACK-DUKE” - “Plaintext Algorithm Cipher Key - Decoding Using Key for Extraction”
Question 5(c) [7 marks]#
Write a short-note on 1) E-mail and 2) DNS
Answer: 1) E-mail (Electronic Mail):
E-mail is a method of exchanging digital messages over a communication network.
Diagram:
| Component | Function |
|---|---|
| Mail User Agent (MUA) | Email client software used by end-users |
| Mail Transfer Agent (MTA) | Server software that transfers emails |
| Mail Delivery Agent (MDA) | Delivers email to recipient’s mailbox |
| Protocols | SMTP (sending), POP3/IMAP (receiving) |
- Structure: Headers (To, From, Subject) and Body
- Security: Features like encryption (TLS), authentication (SPF, DKIM)
- Attachments: Binary files encoded for text transmission
- Features: Forwarding, filtering, organizing, searching
2) DNS (Domain Name System):
DNS is a hierarchical and decentralized naming system for translating domain names to IP addresses.
Diagram:
| DNS Component | Function |
|---|---|
| Root Servers | Top of DNS hierarchy |
| TLD Servers | Manage top-level domains (.com, .org) |
| Authoritative Servers | Store DNS records for specific domains |
| Recursive Resolvers | Query other servers to resolve domain names |
| DNS Records | Resource records (A, AAAA, MX, CNAME, etc.) |
- Purpose: Map human-readable names to machine-readable addresses
- Resolution Process: Recursive or iterative queries through hierarchy
- Caching: Temporary storage of results to improve performance
- Security: DNSSEC provides authentication and integrity
Mnemonic: “MAPS” - “Mail needs Addresses, Protocols, and Servers” Mnemonic: “HARD” - “Hierarchy, Addressing, Resolution, Distributed system”
Question 5(a) OR [3 marks]#
What do you mean by security topology and security zone?
Answer: Security topology and security zones are network security concepts that organize and protect network resources.
| Concept | Definition | Examples |
|---|---|---|
| Security Topology | Physical and logical arrangement of security controls | DMZ, Defense-in-depth |
| Security Zone | Segment of network with specific security requirements | DMZ, Intranet, Extranet |
Diagram:
- Security Topology: Overall security architecture design
- Security Zones: Logical boundaries with consistent security policies
- Defense-in-depth: Multiple layers of security controls
Mnemonic: “TIPS” - “Topology Isolates and Protects Systems”
Question 5(b) OR [4 marks]#
Write short-note on Voice and Video IP.
Answer: Voice and Video over IP (VoIP/Video IP) refers to technologies for transmitting voice and video communications over IP networks.
Diagram:
| Component | Function |
|---|---|
| Codecs | Encode/decode audio and video (G.711, H.264) |
| Signaling Protocols | Call setup/teardown (SIP, H.323) |
| Transport Protocol | Real-time media transport (RTP/RTCP) |
| QoS Mechanisms | Prioritize voice/video traffic |
Voice over IP (VoIP):
- Benefits: Cost savings, flexibility, integration with apps
- Challenges: Latency, jitter, packet loss
- Applications: IP phones, softphones, conferencing
Video over IP:
- Types: Video conferencing, streaming, surveillance
- Requirements: Higher bandwidth, low latency
- Technologies: WebRTC, SIP video, RTSP streaming
Mnemonic: “CLEAR” - “Codecs compress, Latency matters, Encodes audio/video, Applications integrate, Real-time transport”
Question 5(c) OR [7 marks]#
What is IP security? Explain in detail.
Answer: IP Security (IPsec) is a suite of protocols designed to secure IP communications by authenticating and encrypting each IP packet.
Diagram:
| IPsec Protocol | Function | Protection |
|---|---|---|
| Authentication Header (AH) | Data integrity, authentication | No encryption |
| Encapsulating Security Payload (ESP) | Confidentiality, integrity, authentication | Encrypts data |
| Internet Key Exchange (IKE) | Key exchange, SA negotiation | Secure key management |
IPsec Modes:
| Mode | Description | Use Case |
|---|---|---|
| Transport Mode | Protects payload only | Host-to-host communications |
| Tunnel Mode | Protects entire packet | Site-to-site VPNs, remote access |
Security Services:
- Authentication: Verifies identity of communicating entities
- Confidentiality: Protects data from unauthorized disclosure
- Data Integrity: Ensures data hasn’t been altered in transit
- Replay Protection: Prevents packet replay attacks
- Access Control: Limits access to network resources
Applications:
- VPNs: Remote access and site-to-site connections
- Secure Routing: Protects routing protocols
- Secure Host-to-Host: End-to-end security
Mnemonic: “AVID TC” - “Authentication, Verification, Integrity, Datagram protection, Transport mode, Confidentiality”