How to determine the number of devices allowed in a subnet based on its mask?

The number of permissible devices in a subnet is determined by the number of available IP addresses that can be used for hosts. To do this:

1. Determine the number of bits allocated for hosts. The subnet mask is written as /N, where N is the number of bits allocated for the network.
2. Number of bits for hosts = 32 - N (for IPv4).
3. Number of addresses = 2^(number of bits for hosts).
4. Subtract 2 addresses from this number: one for the network address (all host bits 0), and one for the broadcast address (all host bits 1).

Example: mask /24 (255.255.255.0)

• Bits for hosts: 32 - 24 = 8
• Addresses: 2^8 = 256
• Permissible devices: 256 - 2 = 254

Thus, a subnet with a /24 mask can connect 254 devices.