How to Calculate a Subnet Mask from IP Address?

Answer: Calculate a subnet mask from an IP address by determining the number of network bits based on the subnet size and converting them to binary.

To calculate a subnet mask from an IP address, you first need to understand subnetting and binary conversion.

Determine Subnet Size

Decide on the desired subnet size, typically represented as a CIDR notation (e.g., /24 for a subnet with 256 IP addresses).

Convert CIDR Notation to Binary

Convert the CIDR notation to binary. For example, /24 translates to 24 network bits (11111111.11111111.11111111.00000000).

Fill Subnet Mask

Fill in the network bits with “1” and the host bits with “0” to create the subnet mask. In the example of /24, the subnet mask becomes 255.255.255.0 in decimal notation.

Example Calculation

For instance, to calculate the subnet mask for the IP address 192.168.1.0/24:

Convert /24 to binary: 11111111.11111111.11111111.00000000

Fill in the subnet mask: 255.255.255.0

Conclusion

Calculating a subnet mask from an IP address involves understanding CIDR notation, binary conversion, and subnetting principles. The subnet mask is crucial for defining the network boundaries and determining the available IP addresses within a subnet. Understanding how to calculate subnet masks is essential for network administrators and engineers to efficiently manage and configure IP networks.