Introduction to IP Addressing

1. What is an IP address?

• An IP address is a unique numerical identifier for a device on a network.
• In IPv4, it consists of 32 bits, divided into 4 bytes (e.g., 192.168.1.1).

2. Structure of an IP address

An IP address is divided into two parts:

• Network part: identifies the network
• Host part: identifies the device in the network

Example:
IP address: 192.168.1.1 with a /24 mask
Network portion: 192.168.1
Host portion: .1

3. The subnet mask

The mask determines the boundary between the network part and the host part.

Examples:
/24 = 255.255.255.0 → 256 addresses (254 usable)
/26 = 255.255.255.192 → 64 addresses (62 usable)

4. Network address

This is the first address of a subnet (host bits = 0).

It identifies the network itself → not assignable to a machine.

5. Broadcast address

This is the last address in a subnet (host bits = 1).

It allows a message to be sent to all hosts on the network.

6. Range of usable addresses

These are the IP addresses between the network address and the broadcast address.

These are the addresses that can be assigned to devices (PCs, printers, routers, etc.).

7. Private addresses

Some addresses are reserved for internal use (not routable on the Internet).