A subnet mask of 255.255.255.240 is equivalent to which CIDR notation?

The subnet mask of 255.255.255.240 corresponds to a CIDR notation of /28. This is derived from the binary representation of the subnet mask. In binary, 255.255.255.240 is represented as:

• 255: 11111111

• 255: 11111111

• 255: 11111111

• 240: 11110000

When we count the number of '1' bits (which represent the network portion) in this mask, we see that there are 28 bits set to '1'. Hence, the CIDR notation, which expresses the number of bits in the subnet mask, is /28. This indicates that the first 28 bits of the IP address are used for the network part, while the remaining bits are used for host addresses within that subnet.

Understanding this conversion between subnet masks and CIDR notation can greatly assist in subnetting networks efficiently, enabling you to determine how many subnets are available as well as the number of possible hosts in each subnet.