Select which of the following are public IP addresses:

A public IP address is an address that is routable on the internet and is not reserved for private use within local networks. The correct choice, which is 11.63.72.21, is categorized as a public IP address because it falls within the range of IP addresses that are not designated for private networks.

In contrast, the other options provided are private IP addresses:

• 172.168.254.2 and 172.28.73.21 both fall within the range of 172.16.0.0 to 172.31.255.255, which is designated for private use according to the Internet Assigned Numbers Authority (IANA).

• 10.110.50.37 is another private IP address, as it falls within the 10.0.0.0 to 10.255.255.255 range.

Thus, only 11.63.72.21 is a public IP address, as it is outside the ranges reserved for private networks and can be accessed over the internet.