What does it mean when a network address is described as non-routable?

A network address described as non-routable signifies that it is designated for use only within a local network and cannot be used to communicate across the wider internet. Non-routable addresses are typically reserved for private networks, such as those defined by the RFC 1918 standard. These address ranges include 10.0.0.0 to 10.255.255.255, 172.16.0.0 to 172.31.255.255, and 192.168.0.0 to 192.168.255.255. Devices using these addresses can communicate with each other within the same local area network (LAN), but they cannot be directly reached from external networks like the internet without the use of Network Address Translation (NAT) or a similar method.

In contrast to non-routable addresses, options that imply specific conditions like requiring a VPN, being temporary, or being used only for external data transmission do not accurately reflect the nature of non-routable addresses. They serve distinct purposes and are not inherently linked to the definition of non-routable network addresses. Thus, understanding the concept of non-routable addresses primarily highlights the restriction of communication to local networks, which is accurately captured by