How many usable addresses does a CIDR /22 subnet allow?

A CIDR /22 subnet provides a total of 2^(32 - 22) IP addresses, which equals 2^10, resulting in 1024 total addresses. However, within any IPv4 subnet, two addresses are reserved: one for the network address and one for the broadcast address. The network address is the first address in the subnet, while the broadcast address is the last address.

Thus, to find the number of usable addresses in a /22 subnet, you subtract these two reserved addresses from the total. Therefore, the calculation is 1024 total addresses minus 2 reserved addresses, resulting in 1022 usable addresses.

However, it appears that there was an error in the provided options, as none correctly state this value. The correct answer for the number of usable addresses in a /22 subnet is 1022, not 1020. Therefore, while 1020 may have been suggested as the answer, it does not accurately reflect the calculation based on CIDR notation principles.