Subnet Mask Table

The following table provides a quick reference guide for subnet masks and their corresponding CIDR notation from /30 up to /8. It helps determine the number of available IP addresses, total network size, and broadcast addresses within a subnet.

IPv4

Example:

The subnet: 192.168.5.0/30 has 4 addresses

192.168.5.0 – Network Address

192.168.5.1 – Gateway

192.168.5.2 – Usable IP

192.168.5.3 – Broadcast

More information:

1. Network Address: The network address represents the starting address of a subnet. It is used to identify the network itself and cannot be assigned to a host.
2. CIDR Notation: CIDR (Classless Inter-Domain Routing) notation represents the subnet mask using a combination of an IP address and a slash (“/”) followed by the prefix length. For example, the CIDR notation “192.168.10.0/30” signifies a subnet with a prefix length of 30.
3. Usable IP Addresses: The usable IP addresses are the range of IP addresses that can be assigned to devices within a subnet. These IP addresses exclude the network and broadcast addresses.
4. Broadcast Address: The broadcast address represents the last address in a subnet and is used to send a message to all devices within that subnet. It cannot be assigned to a host.
5. Total IP Addresses: The total IP addresses in a subnet refer to the sum of usable IP addresses, network address, and broadcast address. It provides an overview of the size of the subnet.