What is the prefix length of a class C IPv4 address?

A Class C IPv4 address is characterized by its default subnet mask, which is 255.255.255.0. This subnet mask corresponds to a prefix length of /24. In Classful networking, Class C addresses are typically used for smaller networks, allowing for 256 addresses (including the network and broadcast addresses), thus facilitating efficient use in environments where a smaller number of hosts are needed.

When referencing the subnet mask in CIDR (Classless Inter-Domain Routing) notation, the /24 indicates that the first 24 bits of the address are used for the network portion, with the remaining 8 bits reserved for host addresses. This structure is what defines the distinct characteristics of Class C addresses, making /24 the appropriate choice for designation.