Which of these is a Class C subnet mask?

A Class C subnet mask is defined as having a prefix length of /24. This means that the first 24 bits of the IP address are used for the network portion, while the remaining 8 bits are used for host addresses within that network. In binary, a Class C subnet mask looks like this: 255.255.255.0, which corresponds to /24.

This designation allows for a relatively small number of hosts (256 total addresses, 254 usable) within a single subnet, making it suitable for smaller networks. Understanding subnetting is crucial for network management, as it helps in efficiently organizing and allocating IP addresses within a network. Other subnet masks, such as /8, /12, and /16, correspond to Class A and Class B addresses, which are used for larger networks and thus do not apply to Class C designations.