Computer Networks is an important topic for Bihar STET Computer Science preparation. It covers concepts such as network types, topologies, OSI and TCP/IP models, transmission media, networking devices, IP addressing, protocols, routing, network security and common Internet services.
These Bihar STET Computer Network Notes 2026 provide quick revision material along with important MCQs.
What is a Computer Network?
A computer network is a collection of interconnected computers and devices that communicate and share resources using communication protocols.
Advantages of Computer Networks
Resource sharing
File and data sharing
Hardware sharing
Communication
Centralized management
Internet access
Improved collaboration
Types of Computer Networks
1. PAN – Personal Area Network
A PAN covers a very small area around an individual.
Example: Bluetooth connection between a phone and wireless earbuds.
2. LAN – Local Area Network
A LAN covers a limited geographical area such as:
Home
School
Office
Computer laboratory
LANs generally provide high-speed communication within the local area.
3. MAN – Metropolitan Area Network
A MAN covers a larger area than a LAN, typically across a city or metropolitan region.
4. WAN – Wide Area Network
A WAN covers a large geographical area such as multiple cities, countries or continents.
The Internet is the most prominent example of a global interconnected network.
Network Topologies
Network topology describes how devices are arranged and connected.
Bus Topology
All devices share a common backbone cable.
Advantage: Simple and relatively inexpensive.
Disadvantage: Failure of the backbone can affect the entire network.
Star Topology
All devices connect to a central device such as a switch.
Advantage: Failure of one connecting cable generally affects only that device.
Disadvantage: Failure of the central device can affect the network.
Ring Topology
Devices are connected in a circular arrangement.
Mesh Topology
Devices are connected through multiple links.
Advantage: High redundancy and reliability.
Disadvantage: Expensive and complex.
Tree Topology
A hierarchical combination of network segments, often resembling branches of a tree.
Network Devices
Hub
A hub broadcasts incoming data to all connected ports.
Switch
A switch forwards Ethernet frames based on MAC addresses.
Router
A router forwards packets between different networks based on network-layer information.
Repeater
A repeater regenerates or retransmits signals to extend communication distance.
Bridge
A bridge connects network segments and filters traffic based on MAC addresses.
Gateway
A gateway can connect networks or systems using different protocols or architectures.
Modem
A modem performs modulation and demodulation for communication over suitable transmission systems.
OSI Model
The OSI (Open Systems Interconnection) model consists of seven layers.
From top to bottom:
Application
Presentation
Session
Transport
Network
Data Link
Physical
Easy Mnemonic
A P S T N D P
“All People Seem To Need Data Processing”
1. Application Layer
Provides network services directly to applications.
Examples:
HTTP
FTP
SMTP
DNS
2. Presentation Layer
Responsible for functions such as:
Data translation
Encryption/decryption
Compression
3. Session Layer
Establishes, manages and terminates communication sessions.
4. Transport Layer
Provides end-to-end transport services.
Important protocols:
TCP
UDP
5. Network Layer
Responsible for logical addressing and routing.
Example: IP
6. Data Link Layer
Responsible for framing and MAC addressing.
Common technologies include Ethernet and Wi-Fi at the lower layers of their protocol operation.
7. Physical Layer
Deals with transmission of raw bits over the physical medium.
TCP/IP Model
The TCP/IP protocol suite is commonly described using four layers:
Application
Transport
Internet
Network Access / Link
Important protocols include:
HTTP/HTTPS
DNS
FTP
SMTP
TCP
UDP
IP
ICMP
ARP
TCP and UDP
TCP – Transmission Control Protocol
TCP is:
Connection-oriented
Reliable
Ordered
Provides flow and congestion control
TCP is used where reliable delivery is important.
Examples:
Web communication using TCP-based HTTP/HTTPS
Email
File transfer
UDP – User Datagram Protocol
UDP is:
Connectionless
Lightweight
Generally lower overhead than TCP
Does not guarantee delivery or ordering
It is useful where low overhead or latency is important.
Examples include:
DNS queries
Streaming and real-time applications
Online gaming
IP Address
An IP address identifies an interface on an IP network.
IPv4
IPv4 uses a 32-bit address.
Example:
192.168.1.10
IPv4 addresses are generally written in dotted-decimal notation.
IPv6
IPv6 uses a 128-bit address.
Example:
2001:db8::1
IPv6 was developed to provide a much larger address space than IPv4.
MAC Address
A MAC (Media Access Control) address is a link-layer address associated with a network interface.
A traditional Ethernet MAC address is 48 bits long and is commonly written in hexadecimal form.
Example:
00:1A:2B:3C:4D:5E
Public and Private IP Addresses
Private IPv4 Address Ranges
Common private IPv4 ranges are:
10.0.0.0/8172.16.0.0/12192.168.0.0/16
Private addresses are commonly used inside local networks.
Public IP Address
A public IP address is globally routable on the Internet, subject to network routing and provider policies.
Network Protocols
A protocol is a set of rules that defines how devices communicate.
HTTP
HyperText Transfer Protocol is used for transferring web resources.
HTTPS
HTTPS is HTTP protected using TLS, providing encryption and authentication for the connection.
FTP
File Transfer Protocol is used for transferring files.
SMTP
Simple Mail Transfer Protocol is primarily used for sending email.
POP3
Post Office Protocol version 3 is used for retrieving email, typically by downloading messages to a client.
IMAP
Internet Message Access Protocol allows email to remain managed on the server while clients synchronize mailbox contents.
DNS
Domain Name System translates domain names into IP addresses and performs other name-resolution functions.
DHCP
Dynamic Host Configuration Protocol automatically provides network configuration such as IP addresses to clients.
ARP
Address Resolution Protocol is used in IPv4 networks to determine the link-layer address associated with an IPv4 address on the local network.
ICMP
Internet Control Message Protocol is used for network-layer control, diagnostics and error reporting.
Ports
A port number identifies a network service endpoint at the transport layer.
Common ports:
| Service | Port |
|---|---|
| HTTP | 80 |
| HTTPS | 443 |
| FTP Control | 21 |
| SSH | 22 |
| SMTP | 25 |
| DNS | 53 |
| DHCP Server | 67 |
| DHCP Client | 68 |
| POP3 | 110 |
| IMAP | 143 |
Transmission Media
Transmission media are broadly classified into two categories.
Guided Media
Data travels through a physical medium.
Examples:
Twisted Pair Cable
Coaxial Cable
Optical Fiber
Twisted Pair
Commonly used in Ethernet networks.
Coaxial Cable
Uses a central conductor surrounded by insulation and shielding.
Optical Fiber
Uses light to transmit data.
Advantages:
High bandwidth
Long-distance transmission
Low susceptibility to electromagnetic interference
Unguided Media
Data is transmitted wirelessly.
Examples:
Radio waves
Microwaves
Infrared
Satellite communication
Network Switching
Circuit Switching
A dedicated communication path is established for the duration of a communication session.
Packet Switching
Data is divided into packets that are transmitted through a shared network.
The Internet primarily uses packet switching.
Routing
Routing is the process of selecting paths for packets through a network.
Static Routing
Routes are manually configured.
Dynamic Routing
Routes are learned and updated using routing protocols.
Examples of routing protocols include:
RIP
OSPF
BGP
RIP
Routing Information Protocol is a distance-vector routing protocol.
OSPF
Open Shortest Path First is a link-state interior gateway protocol.
BGP
Border Gateway Protocol is used for exchanging routing information between autonomous systems.
Network Security
Network security protects systems, networks and data against unauthorized access and attacks.
Important concepts include:
Authentication
Authorization
Encryption
Firewall
Antivirus/anti-malware
Intrusion detection
Secure protocols
Firewall
A firewall monitors and controls network traffic according to configured security rules.
Encryption
Encryption converts readable data into a protected form using cryptographic techniques.
Authentication
Authentication verifies the identity of a user, device or system.
Important Computer Network MCQs for Bihar STET 2026
1. What is a computer network?
A. A single computer
B. A collection of interconnected devices
C. Only an Internet browser
D. A computer program
Answer: B. A collection of interconnected devices
2. Which network covers a small geographical area such as an office?
A. WAN
B. MAN
C. LAN
D. PAN only
Answer: C. LAN
3. What does WAN stand for?
A. Wide Area Network
B. Wireless Area Node
C. Web Access Network
D. Wide Access Node
Answer: A. Wide Area Network
4. Which topology uses a central connecting device?
A. Bus
B. Ring
C. Star
D. Mesh
Answer: C. Star
5. Which device forwards Ethernet frames based on MAC addresses?
A. Router
B. Switch
C. Modem
D. Repeater
Answer: B. Switch
6. Which device is primarily responsible for routing packets between networks?
A. Hub
B. Router
C. Repeater
D. Bridge
Answer: B. Router
7. How many layers are present in the OSI model?
A. 4
B. 5
C. 6
D. 7
Answer: D. 7
8. Which is the lowest layer of the OSI model?
A. Network
B. Data Link
C. Physical
D. Transport
Answer: C. Physical
9. Which OSI layer is responsible for routing?
A. Physical
B. Data Link
C. Network
D. Session
Answer: C. Network
10. Which OSI layer uses MAC addressing?
A. Physical
B. Data Link
C. Network
D. Transport
Answer: B. Data Link
11. Which protocol is connection-oriented?
A. UDP
B. TCP
C. IP
D. ICMP
Answer: B. TCP
12. Which protocol is connectionless?
A. TCP
B. UDP
C. FTP
D. SMTP
Answer: B. UDP
13. What is the size of an IPv4 address?
A. 16 bits
B. 32 bits
C. 64 bits
D. 128 bits
Answer: B. 32 bits
14. What is the size of an IPv6 address?
A. 32 bits
B. 64 bits
C. 128 bits
D. 256 bits
Answer: C. 128 bits
15. What is the traditional size of an Ethernet MAC address?
A. 16 bits
B. 32 bits
C. 48 bits
D. 128 bits
Answer: C. 48 bits
16. Which protocol translates domain names into IP addresses?
A. FTP
B. DNS
C. DHCP
D. SMTP
Answer: B. DNS
17. Which protocol automatically assigns IP configuration to network clients?
A. DNS
B. DHCP
C. FTP
D. HTTP
Answer: B. DHCP
18. Which protocol is primarily used to send email?
A. SMTP
B. POP3
C. IMAP
D. HTTP
Answer: A. SMTP
19. Which protocol is commonly used to retrieve email while keeping mailbox synchronization on the server?
A. SMTP
B. IMAP
C. FTP
D. DHCP
Answer: B. IMAP
20. What is the default port for HTTP?
A. 21
B. 22
C. 80
D. 443
Answer: C. 80
21. What is the default port for HTTPS?
A. 25
B. 53
C. 110
D. 443
Answer: D. 443
22. Which protocol is commonly associated with secure remote login?
A. SSH
B. FTP
C. SMTP
D. DHCP
Answer: A. SSH
23. Which transmission medium uses light signals?
A. Coaxial cable
B. Twisted pair
C. Optical fiber
D. Radio wave
Answer: C. Optical fiber
24. Which technology is primarily associated with wireless communication?
A. Optical fiber
B. Radio waves
C. Coaxial cable
D. Twisted pair
Answer: B. Radio waves
25. The Internet primarily uses which switching technique?
A. Circuit switching
B. Packet switching
C. Message switching only
D. Manual switching
Answer: B. Packet switching
26. Which protocol is used for IPv4 address-to-MAC address resolution on a local network?
A. DNS
B. ARP
C. DHCP
D. FTP
Answer: B. ARP
27. Which protocol is used for network control and diagnostic messages?
A. ICMP
B. SMTP
C. FTP
D. POP3
Answer: A. ICMP
28. Which routing protocol is a link-state protocol?
A. RIP
B. OSPF
C. FTP
D. DHCP
Answer: B. OSPF
29. Which protocol is used for inter-domain routing?
A. RIP
B. OSPF
C. BGP
D. ARP
Answer: C. BGP
30. Which device broadcasts incoming data to all connected ports?
A. Router
B. Switch
C. Hub
D. Gateway
Answer: C. Hub
Quick Revision – Computer Network One-Liners
PAN → Personal Area Network.
LAN → Local Area Network.
MAN → Metropolitan Area Network.
WAN → Wide Area Network.
OSI → 7-layer reference model.
TCP → Reliable, connection-oriented transport protocol.
UDP → Connectionless transport protocol.
IPv4 → 32-bit address.
IPv6 → 128-bit address.
MAC Address → Link-layer address; traditional Ethernet MAC is 48 bits.
DNS → Domain name resolution.
DHCP → Automatic network configuration.
HTTP → Web protocol.
HTTPS → HTTP secured with TLS.
FTP → File transfer protocol.
SMTP → Sending email.
POP3 → Email retrieval/download protocol.
IMAP → Server-based email access and synchronization.
ARP → IPv4 address to MAC address resolution on local networks.
ICMP → Network control and diagnostic messages.
Switch → Forwards frames using MAC addresses.
Router → Connects networks and forwards packets.
Hub → Broadcasts data to connected ports.
Firewall → Controls network traffic according to security rules.
BFS → Commonly uses a queue.
RIP → Distance-vector routing protocol.
OSPF → Link-state routing protocol.
BGP → Inter-domain routing protocol.
Fiber Optic → Uses light for data transmission.
Bihar STET Computer Network Preparation Tips
For Bihar STET Computer Science, focus particularly on OSI and TCP/IP models, network topologies, LAN/MAN/WAN, networking devices, TCP/UDP, IPv4/IPv6, MAC addressing, common protocols, ports, transmission media, switching, routing and network security.
Most Important Topics
Computer Network Basics
LAN, MAN, WAN and PAN
Network Topologies
Network Devices
OSI Model
TCP/IP Model
TCP and UDP
IPv4 and IPv6
MAC Address
DNS and DHCP
HTTP and HTTPS
FTP, SMTP, POP3 and IMAP
ARP and ICMP
Transmission Media
Circuit and Packet Switching
Routing
RIP, OSPF and BGP
Network Security
Firewall
Common Port Numbers
