A subnet mask of 255.255.255.254 is equivalent to which CIDR notation?

A subnet mask of 255.255.255.254 can be represented in CIDR notation as /31. CIDR (Classless Inter-Domain Routing) notation indicates the number of bits set to 1 in the subnet mask. In the binary representation of 255.255.255.254, which is 11111111.11111111.11111111.11111110, there are 31 bits set to 1. As a result, the correct representation of this subnet mask in CIDR notation is /31.

The use of /31 is particularly significant in point-to-point links, where only two hosts are connected, as it allows for efficient use of IP address space without wasting an address. Subnets with /31 can effectively utilize two IP addresses for each end of the link, which fits perfectly for this configuration.

The other CIDR notations such as /30, /32, and /29 represent different subnet masks and IP address ranges, which do not match the specific configuration of 255.255.255.254. Therefore, /31 is the correct answer.