In the CIDR notation 172.16.10.0/24, what is the prefix length?

The prefix length in CIDR notation indicates the number of bits used for the subnet mask. In the example provided, 172.16.10.0/24 specifies that the first 24 bits of the address are used for the network portion. This means that in a 32-bit IPv4 address, the remaining 8 bits are available for host addresses within that network.

In CIDR, the notation "/n" where "n" represents the prefix length, helps in determining the size of the subnet and how many IP addresses are available in that subnet. A prefix length of 24 corresponds to a subnet mask of 255.255.255.0, which allows for 256 addresses in total (from 0 to 255), though typically only 254 of these can be assigned to hosts since two addresses are reserved (the network address and the broadcast address).

The other options do not accurately represent the prefix length in CIDR notation. The option that states "0 to 255" refers to the range of IP addresses within the subnet but does not define the prefix length itself. The other option specifying 256 is also a common misunderstanding, as it relates to the total number of addresses as mentioned rather than the prefix length component.