Computer Networks-I Notes
Subject Overview
Computer Networks-I introduces networking fundamentals — the OSI and TCP/
Subject at a glance
4
Units
30
Topics
3
Credits
4
Infographics
Unit-wise Syllabus
4 units — open any unit for detailed topic-wise notes, diagrams and important exam questions
- Definition and objectives of computer networks
- network components and architecture
- OSI model layers and functions
- TCP/IP model layers and functions
- comparison of OSI and TCP/IP
- physical vs logical topologies (star, ring, bus, mesh, hybrid) and their trade-offs
- 7 Application
HTTP, FTP, SMTP
- 6 Presentation
Encryption, compression
- 5 Session
Opening and closing sessions
- 4 Transport
TCP, UDP
- 3 Network
IP addressing and routing
- 2 Data link
MAC addressing, frames
- 1 Physical
Cables, signals, bits
Study guide
This unit explains how computers talk to each other. You learn the definition and objectives of computer networks, network components and architecture, the seven layers of the OSI model and four layers of the TCP/IP model with their functions, how they compare, and physical versus logical topologies (star, ring, bus, mesh, hybrid) and their trade-offs. Memorise the OSI layers in order with one function for each; it is asked every year.
- Analog vs digital signals
- transmission modes (simplex, half-duplex, full-duplex)
- bandwidth and latency
- routers
- switches
- hubs
- bridges
- gateways — functions and configuration
Hub
Layer 1
Repeats signals to every port
Switch
Layer 2
Forwards frames using MAC addresses
Router
Layer 3
Routes packets between networks using IP
Study guide
Data has to be turned into signals and moved through devices. You study analog and digital signals, transmission modes (simplex, half-duplex, full-duplex), bandwidth and latency, and the functions and configuration of routers, switches, hubs, bridges and gateways. Be able to say which OSI layer each device works at.
- Functions of the data link layer
- framing
- error detection and correction
- flow control
- Ethernet standards and frame structure
- MAC addressing and ARP
- Ethernet switching
- Framing
- Splitting data into frames
- MAC address
- 48-bit hardware address of a network card
- ARP
- Finds the MAC address for an IP address
- CRC
- Detects transmission errors
- Flow control
- Stops a fast sender overwhelming a slow receiver
Study guide
The data link layer delivers frames between devices on the same network. You study its functions, framing, error detection and correction, flow control, Ethernet standards and frame structure, MAC addressing and ARP, and Ethernet switching. Practise a parity or CRC error-detection example by hand.
- TCP/IP protocol suite
- IPv4 and IPv6 addressing
- subnetting and CIDR notation
- ARP operation and table
- ARP spoofing and security
- VLAN concepts
- tagging
- configuration
- benefits and use cases
Address size
32 bits
128 bits
Notation
Dotted decimal: 192.168.1.1
Hexadecimal: 2001:db8::1
Address space
About 4.3 billion
Practically unlimited
Configuration
Manual or DHCP
Auto-configuration built in
Study guide
Protocols are the agreed rules of networking. You study the TCP/IP suite, IPv4 and IPv6 addressing, subnetting and CIDR notation, how ARP works and how ARP spoofing attacks it, and VLAN concepts, tagging, configuration, benefits and use cases. Subnetting is numerical and examined often, so practise many examples.
Why Computer Networks-I Matters
Networking is the backbone of the internet, cloud and cybersecurity. Network fundamentals such as OSI, TCP/IP, IP addressing and subnetting are tested in nearly every IT interview and are the base for certifications such as CCNA.
How to Prepare for Computer Networks-I
- Learn the OSI and TCP/IP layers with their protocols and devices in one table.
- Practise subnetting problems daily until they take under two minutes.
- Draw each topology and list its advantages and disadvantages.
- Use a tool such as Cisco Packet Tracer to see these ideas work.
Computer Networks-I: Frequently Asked Questions
What is the difference between the OSI and TCP/IP models?
OSI is a seven-layer reference model, while TCP/IP is a four-layer practical model on which the internet runs. Their layers map roughly but not exactly.
What is subnetting?
Subnetting divides a larger IP network into smaller sub-networks to use addresses efficiently and improve performance and security.
Which topology is most common in modern networks?
The star topology, in which devices connect to a central switch, is the most widely used in modern LANs.