How can a name server be described when it contains resource records for a specific namespace?

A name server that contains resource records for a specific namespace is classified as an authoritative server. This designation signifies that the server holds complete and accurate information about the namespace it serves, including details like domain names, corresponding IP addresses, and other related records. When a name server is authoritative, it means it can provide definitive answers to queries about the namespace without needing to reference other servers.

In contrast, non-authoritative servers may cache information from authoritative sources and provide responses based on that cached data but do not hold the original records. A router, on the other hand, is a networking device that directs data traffic between different networks and isn't directly involved in name resolution. Lastly, calling this type of technology "obsolete" is inaccurate, as authoritative name servers play a crucial role in the functioning of the Domain Name System (DNS) and are integral to internet connectivity and navigation.