What does a slash character in a CIDR notation denote?

In CIDR (Classless Inter-Domain Routing) notation, the slash character is a crucial component that indicates the number of bits used for the network identifier in an IP address. The format typically looks like this: /, where is the number of bits set to '1' in the subnet mask.

For example, in the CIDR notation 192.168.1.0/24, the "/24" denotes that the first 24 bits of the IP address are reserved for the network identifier, allowing for a specific range of IP addresses to be part of that network. This method provides more flexibility and efficient use of IP address spaces compared to traditional classful addressing, where networks are divided into fixed sizes.

Understanding this notation is vital for network design and administration, as it directly influences how subnets are organized and how IP addresses are distributed within a given network. Therefore, the slash character effectively conveys essential information about how many bits are utilized for identifying the specific network, which is why the correct answer is that it denotes the number of bits used for the network identifier.