DIT Part-I Computer Networks Solved Paper 2026 - TCP IP OSI LAN WAN [1st Term]

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Paper: Computer Networks - (Part-I) - 1st Term Examination 2026 - DIT Part-I
Time Allowed: Part-A 20 Minutes, Part-B & C 02 Hrs & 40 Minutes | Total Marks: 75 (Part-A 15 + Part-B & C 60). Fully solved as per KPBTE standard.

Part-A Q.1 a) Fill in the Blanks

i IP stands for ______

Answer: Internet Protocol - It is the protocol that provides addressing and routing of packets on the network.

ii TCP stands for ______

Answer: Transmission Control Protocol - Connection-oriented, reliable protocol of Transport Layer.

iii IPv6 was introduced to address the limited availability of ______ addresses.

Answer: IPv4 - IPv4 has only 32-bit (4.3 billion) addresses which are exhausted, IPv6 was introduced to solve this.

iv IPv6 is ______ bits long.

Answer: 128 bits - IPv4 is 32 bits, IPv6 is 128 bits long, providing 340 undecillion addresses.

v UDP stands for ______

Answer: User Datagram Protocol - Connectionless, fast protocol of Transport Layer, used for video streaming, DNS.

vi Coaxial cable, radio waves, and fiber optics are all types of ______ used for data transmission.

Answer: Transmission Media / Communication Media - Coaxial and Fiber are Guided/Wired media, Radio waves are Unguided/Wireless media.

vii The ______ is the person or device that receives the message sent by the sender.

Answer: Receiver / Destination - The final component in communication model.

viii ______ are the rules governing communication.

Answer: Protocols - Set of rules that govern data communication, e.g., TCP/IP.

ix A Hub operates at the ______ of the OSI model.

Answer: Physical Layer (Layer 1) - Hub is a dumb device that broadcasts data to all ports, operates at Physical Layer.

x In OSI model the ______ layer includes protocols for tasks such as file transfers, email and remote login.

Answer: Application Layer (Layer 7) - Top layer of OSI, provides network services to user applications. Protocols: FTP, SMTP, Telnet.

Part-A Q.1 b) Choose / Encircle the correct answer

i. ______ accepts the message.
Ans: c) Receiver
a) Host sender - sends, b) Message - data itself, c) Receiver - accepts, d) Media - channel

ii. ______ initiates transmission of data.
Ans: b) Host / Sender
Sender is the device that initiates communication.

iii. A ______ covers a small geographic area, such as a single building or campus.
Ans: a) LAN - Local Area Network
WAN = large area, MAN = city, PAN = personal (10m)

iv. UDP operates at which layer ______
Ans: b) Transport Layer
Both TCP and UDP work at Transport Layer of TCP/IP & OSI

v. In TCP/IP model, which layer deals with physical connection between devices on same network?
Ans: d) Network Access Layer
Also called Link Layer / Network Interface Layer. Handles physical addressing and connection.

Part-B - Attempt any Six (05 Marks Each)

Q2 i Define Host / Sender

Host/Sender is the device or person who sends the message or data. It is the source of communication. It generates the data and sends it through transmission media to the receiver. Example: A computer sending an email, a mobile phone making a call. In network terminology, any computer connected to network is called a host.

Q2 ii Define Node

A Node is any device connected to a computer network that can send, receive, or forward data. Each node has a unique address (IP/MAC). Examples: Computer, Laptop, Printer, Router, Switch, Server. In a network diagram, every connection point is a node.

Q2 iii Define NIC

NIC stands for Network Interface Card. It is a hardware component that connects a computer to a network. It can be wired (Ethernet card) or wireless (Wi-Fi card). It has a unique MAC address. Without NIC, a computer cannot connect to network. It operates at both Physical and Data Link layers.

Q2 iv Why is selection of Media crucial? Examples

Media is the physical path through which data travels from sender to receiver. Selection of media is crucial because it affects speed, cost, distance, bandwidth, and interference. Wrong media selection can cause data loss and slow communication. Wired Media Example: Twisted Pair Cable (used in LAN, cheap, 100m limit), Fiber Optics (very fast, long distance, expensive). Wireless Media Example: Radio Waves (Wi-Fi, Bluetooth), Microwaves (mobile communication, satellite).

Q2 v Define Modem

Modem stands for Modulator-Demodulator. It is a device that converts digital signals from computer into analog signals for telephone lines (Modulation) and converts analog signals back to digital (Demodulation). It is required to connect to the internet via telephone line. Types: Internal, External, DSL modem.

Q2 vi Define Hub

Hub is a networking device that operates at Physical Layer of OSI model. It connects multiple computers in a star topology. When it receives data from one port, it broadcasts it to all other ports. It is a non-intelligent device, does not filter data. It is cheap but creates more traffic and is now replaced by Switch.

Q2 vii Why is it important for both sender and receiver to adhere to same Protocol?

Protocol is a set of rules governing communication. If sender and receiver do not use same protocol, they cannot understand each other, just like two people speaking different languages. Same protocol ensures: Same data format, Same timing and sequence, Error detection and correction, Successful delivery. Example: Both must use TCP/IP to communicate over internet.

Q2 viii Define IPv6 and why introduced?

IPv6 stands for Internet Protocol Version 6. It is the latest version of Internet Protocol. It uses 128-bit addressing, providing 340 undecillion addresses. It was introduced because IPv4 (32-bit, 4.3 billion addresses) got exhausted due to huge increase in internet devices, mobiles, IoT. IPv6 also provides better security (IPSec), faster routing, and no need for NAT.

Q2 ix Define routing protocol

Routing protocol is a set of rules used by routers to determine the best path for data packets from source to destination. It helps routers share information and build routing tables dynamically. Examples: RIP (Routing Information Protocol), OSPF (Open Shortest Path First), BGP (Border Gateway Protocol).

Q2 x Define twisted pair cable

Twisted Pair Cable is a type of guided/wired transmission media made of pairs of insulated copper wires twisted together to reduce interference. Two types: UTP (Unshielded Twisted Pair) - used in LAN, cheap; STP (Shielded Twisted Pair) - shielded with metal foil, better protection from noise. Used in telephone lines and Ethernet networks. Maximum distance 100 meters.

Part-C - Attempt any Three (10 Marks Each)

Q3 Bus, Star and Ring Topology - Characteristics, Advantages, Limitations

a) Bus Topology: All devices connected to a single central cable (backbone). Data travels in both directions. Characteristics: Single cable, terminators at both ends, easy to install. Advantages: Cheap, less cable needed, easy to add new node. Limitations: If backbone breaks, whole network fails, slow when many users, difficult to troubleshoot.

b) Star Topology: All devices connected to a central device (Hub/Switch). Characteristics: Central controller, each device has dedicated link. Advantages: Easy to install and manage, if one node fails network still works, easy to detect fault. Limitations: If central device fails whole network fails, needs more cable, costly.

c) Ring Topology: Each device connected to two other devices forming a ring. Data travels in one direction. Characteristics: Token passing, each device acts as repeater. Advantages: No collision, equal access to all nodes, good for heavy traffic. Limitations: If one node fails whole ring can fail (unless dual ring), adding/removing node disrupts network, difficult to troubleshoot.

Q4 Concept of computer network and its significance

Definition: A computer network is a group of interconnected computers and devices that can share data, resources, and communicate with each other using transmission media and protocols.
Significance in today's world: 1) Resource Sharing: Share printers, files, internet connection. 2) Communication: Email, video conferencing, social media, WhatsApp are all possible due to networks. 3) E-Commerce & Banking: Online shopping, online banking, ATM networks. 4) Entertainment: Netflix, YouTube, online gaming. 5) Education & Work: Online classes, remote work, Google Classroom. 6) Information Access: World Wide Web, search engines. Without computer networks, modern digital world would collapse. The internet is the largest network connecting billions of devices globally.

Q5 Wireless network topologies - Wi-Fi, Satellite, Radio Wave

Wireless Topology: No physical cables, data transmitted via electromagnetic waves. Devices connect via access points. Types: Infrastructure (with central AP) and Ad-hoc (without AP).

a) Wi-Fi (Wireless Fidelity): Uses radio waves (2.4GHz/5GHz) to connect devices within 100m. Applications: Home internet, offices, colleges, hotspots, mobile phones, laptops.

b) Satellite: Uses satellite in space as repeater. Earth station sends signal to satellite, satellite amplifies and sends back to other earth stations. Covers very large area, entire country/continent. Applications: TV broadcasting (Dish TV), GPS, weather forecasting, remote area internet, military communication.

c) Radio Wave: Uses radio frequencies (3KHz to 1GHz) for wireless communication, omnidirectional. Applications: FM Radio, AM Radio, Bluetooth, Walkie-Talkie, Mobile phones, Wireless headphones.

Q6 Explain TCP/IP Model

TCP/IP stands for Transmission Control Protocol / Internet Protocol. It is the standard model used for internet communication. It has 4 Layers (5-layer model also used):

1. Network Access / Link Layer: Bottom layer, deals with physical connection between devices on same network. Includes protocols for physical addressing (MAC), Ethernet, Wi-Fi. Similar to Physical + Data Link of OSI.

2. Internet Layer: Responsible for logical addressing and routing. Main protocol is IP (IPv4/IPv6). It decides best path for packet. Also includes ICMP, ARP. Similar to Network Layer of OSI.

3. Transport Layer: Provides end-to-end communication and reliability. Two main protocols: TCP (reliable, connection-oriented, used for web, email) and UDP (fast, connectionless, used for video streaming, DNS). Handles segmentation and error control.

4. Application Layer: Top layer, closest to user. Provides network services to applications. Protocols: HTTP (web browsing), FTP (file transfer), SMTP (email sending), POP3 (email receiving), DNS (name resolution), Telnet. It combines Application, Presentation, Session layers of OSI.

Data flows from Application to Network Access at sender side (encapsulation) and reverse at receiver side (decapsulation). TCP/IP is simpler and more practical than OSI and is the backbone of internet.