What is an IP Address?
A letter only reaches you because your house has an address. On a network, millions of devices are sending data to each other, and each piece of data has to find the one device it is meant for. So every device needs an address too.
1What an IP address is
An IP address looks like this: 192.168.0.178 — four numbers with dots between them. The next lesson explains the rules for writing one.
An IP address does two jobs at once. Part of it says which network the device is on, and the rest says which device it is on that network. In a home or school network like the ones below, the first three numbers name the network and the last number names the device:
Unique means no two devices on the same network share an address. If they did, data meant for one could land on the other. Know a device’s IP address, and data can be sent to it from anywhere on its network.
2An IP address can change
Here is the surprising part. An IP address belongs to the device only while it is on that network. Carry a laptop to a different network and it is given a new address that belongs there. Try it.
Send a message to the laptop. Then carry the laptop home and send it again. Drag sideways to turn.
Addresses beginning 192.168 are private addresses, used inside homes and schools. Each network hands out its own set of them, which is why the laptop’s address changes when it moves.
While the laptop was at school, the message to 192.168.1.23 reached it. At home it has 192.168.0.105 instead. The network part changed from 192.168.1 to 192.168.0 because it is a different network, so the old address finds nobody. But look at the violet label: the MAC address never changed.
3IP address vs MAC address
You met the MAC address in Ethernet Card: the address fixed into a network card when it is made. It is easy to mix the two up, so hold on to this: a device has both, and they do different jobs.
- The MAC address is the device’s own physical address. It identifies the network card itself, wherever it goes, and never changes.
- The IP address is a logical address that says where the device is: which network, and which device on that network. It changes when the device moves.
Data needs both. It is sent to an IP address, and routers use the network part to carry it to the right network. Once it has arrived in that network, the device with that IP address is found by its MAC address, and the switch hands the data to it.
| MAC address | IP address | |
|---|---|---|
| Identifies | The device's network card itself | The network the device is on, and the device on it |
| Given by | The manufacturer, burnt into the network card | The network the device joins |
| Changes? | Never — it stays with the card | Yes — when the device moves to another network |
| Also called | Physical address | Logical address |
| Looks like | 00:1A:2B:3C:4D:5E (six pairs, hexadecimal) | 192.168.0.178 (four numbers, dots between) |
| Used by | A switch, to hand data to a device inside one network | Routers, to carry data to the right network |
Think of your Aadhaar number and your postal address
4From the board papers
▶Show the answer
An IP address (Internet Protocol address) is a unique address given to each device on a network that uses the Internet Protocol. It identifies the network the device is on and the device itself, so that data can be sent to it — for example 192.168.0.178.
Reason (R): MAC address is assigned by the manufacturer and is burned into the network interface card, making it a hardware-based address.KV pre-board 2025-26
▶Show the answer
Both A and R are true, and R is the correct explanation of A. It is called a physical address because it is part of the hardware.
5Check yourself
Priya takes a laptop from school to home and connects it to the Wi-Fi there. What happens to the laptop's addresses?
A computer has the IP address 192.168.1.23 on a school network like the one in the lab. What does the 192.168.1 part tell you?
Which of these is written like an IP address?