subnet mask

A subnet mask is a crucial component of Internet Protocol (IP) addressing, acting as a “mask” to separate the network portion of an IP address from the host portion. It is a 32-bit number representing a sequence of 1’s followed by a sequence of 0’s, used to define the boundary of a subnet within a given IP address.

The primary purpose of a subnet mask is to:


The subnet mask is written in the same dotted-decimal format as IP addresses (i.e., four octets separated by dots). For instance, the default subnet mask for a Class A IP address is, for Class B is, and for Class C is

Importance in Cybersecurity

Understanding and configuring subnet masks correctly is crucial in cybersecurity, as they:

To determine the appropriate subnet mask for different requirements, you can use various subnetting tools available online. Proper management of subnet masks is crucial for maintaining a secure, efficient, and well-functioning network.