Explain what a network mask is and how it is used in IP addressing.

A subnet mask is a 32-bit number used in IP addressing to divide an IP address into two parts: network and host.

It determines which part of the IP address belongs to the network and which part belongs to a specific device (host) within that network.

For example, for the IP address 192.168.1.10 with a mask of 255.255.255.0:

• The mask in binary: the first 24 bits are ones, the last 8 are zeros.
• This means the first 24 bits of the IP address define the network (192.168.1), and the last 8 bits define the specific device (10).

Using a mask allows routers and devices to understand which network an address belongs to and how to properly route packets inside and outside the local network.