Which address range is valid for preventing internal LAN computers from communicating directly on the Internet?

The correct answer is based on the context of private IP address ranges defined by the Internet Engineering Task Force (IETF). Private IP addresses are reserved for use within private networks and are not routable on the public Internet, which protects internal LAN computers from direct Internet communication.

The address range that includes 172.16.20.1 through 172.16.20.254 falls under the Class B private address space (specifically, the range from 172.16.0.0 to 172.31.255.255). These addresses can be used within local networks and facilitate communication among devices without exposing them to the global Internet. This allows for enhanced security and the ability to utilize these addresses without concern for conflicts with public Internet addresses.

While the other ranges listed (10.0.0.1 to 10.0.0.254 and 192.168.1.1 to 192.168.1.254) are also valid private address ranges, the specific question about the range provided in the answer highlights the correct context for Class B usage. The range from 169.254.0.1 to 169.254.255.254 refers to link-local addresses, which are intended for use only