Which address range is valid to ensure that computers on your internal LAN cannot communicate directly on the Internet?

The valid addresses to ensure that computers on your internal LAN cannot communicate directly on the Internet belong to private IP address ranges as defined by the Internet Engineering Task Force (IETF). The answer is correct because the address range of 172.16.20.1 through 172.16.20.254 falls within the designated range for private IP addresses, which is 172.16.0.0 to 172.31.255.255.

Private IP addresses have a significant role in networking as they are used within internal networks and are not routable on the public Internet. This means that any device assigned an IP address within this range will not be directly accessible from external networks, effectively isolating the internal LAN from the Internet to enhance security.

Other ranges mentioned, such as those starting with 192.168.1.x, 10.x.x.x, and even certain ranges of 172.x.x.x, are also classified as private address ranges. However, the key factor in selecting the correct answer is that it specifically identifies a segment of the private addressing space that continues to reinforce the concept of internal network isolation.

By selecting the correct range, you're ensuring that your LAN devices can communicate with each other without exposing them to the risks of