Ch 10Computer Networks — Class 12 Computer Science, concept-first.

We live in a connected world. Information is produced, exchanged, and tracked across the globe in real time.

The story of computer networking begins not with the internet we know today, but with a military research project in the 1960s.

A computer network is not defined by the number of devices it connects, but by the geographical area it covers and the data transfer rate it can support — from a handful of handheld devices linked ove…

A Personal Area Network, or PAN, is a network created by connecting a few personal devices that belong to a single person.

A Local Area Network (LAN) is a network that connects devices placed within a limited physical distance.

A Local Area Network (LAN) is limited to a single building or campus. When you need to connect computers across an entire city or a large town, a LAN is no longer sufficient.

A Wide Area Network is the largest scale of computer network. It connects computers and other networks — including Local Area Networks (LANs) and Metropolitan Area Networks (MANs) — that are spread ac…

A network cannot function with just cables and wireless signals. To communicate data through different transmission media and to configure networks with different functionality, we need dedicated hard…

A modem is the device that makes internet access over telephone lines possible. The name itself tells you what it does: MOdulator DEModulator.

An Ethernet card is the physical hardware that lets a computer connect to a wired network. It is also called a Network Interface Card, or NIC for short.

The RJ45 connector is the physical interface used to connect devices to a network cable. It is the most common type of connector for Ethernet networking, and you will find it at the ends of every twis…

A repeater is a simple but essential networking device. Its job is to deal with a physical limitation of cables: signals weaken as they travel, and beyond a certain distance they become too weak to be…

A hub is a simple network device that connects multiple computers or other devices in a wired local area network (LAN).

A switch is a networking device that acts as the central connection point in a Local Area Network (LAN).

A router is a network device that does more than just forward data — it can receive data, analyse it, and transmit it to other networks.

A gateway is exactly what its name suggests — a gate. It is the key access point that connects an organisation’s internal network to the outside world, most commonly the Internet.

A network is more than just a collection of wires and devices — the way those devices and other peripherals are arranged in a network is called its topology.

A mesh topology is built on the principle of direct connection: every device in the network is connected to every other device.

In a ring topology, each node is connected to exactly two other devices — one on its left and one on its right. This creates a closed loop, or ring, of connected nodes.

In a bus topology, every device on the network is connected to a single, shared communication line. This central cable is called the bus or the backbone.

In a star topology, every device on the network is connected to a single central node. That central node is a networking device — typically a hub or a switch.

A network topology is the physical or logical arrangement of devices. When a network is large and complex, it is rarely practical to use a single basic shape like a star or a ring.

Every device connected to a network — a computer, a smartphone, a printer, a router — is called a node. For communication to work, each node must have a unique identity.

The MAC address is the permanent, physical identity of a network device. It is assigned to the network interface card (NIC) at the time of manufacture and never changes.

An IP address (Internet Protocol address) is a unique identifier assigned to each node in a network that uses the Internet Protocol for communication.

The Internet is not just a network of computers. It is the global network of computing devices — that includes desktops, laptops, servers, tablets, mobile phones, printers, scanners, routers, switches…

The World Wide Web is not the Internet. That is the single most important distinction to hold from the start.

The Internet is a vast collection of servers, each storing websites and other resources. Every server — indeed every device connected to the Internet — has a unique IP address.

Computers communicate using IP addresses, but humans find it far easier to remember names. Instead of memorising a string of numbers like 164.100.60.233, we assign a domain name to each IP address — f…

- Networks and nodes: A computer network is an interconnection among two or more computers or computing devices that lets them share data and resources.

Sample papers and previous-year board questions for this subject.