It translates an often humanly meaningful, text-based identifier to a system-internal, often numeric identification or addressing component.
The Internet maintains two principal namespaces: the domain name hierarchy[1] and the IP address system.
The contents of a zone are either manually configured by an administrator, or managed using Dynamic DNS.
However, with only authoritative name-servers operating, every DNS query must start with recursive queries at the root zone of the Domain Name System and each user system must implement resolver software capable of recursive operation.
[clarification needed] Caching name servers (DNS caches) are usually recursive resolvers that store DNS query results for a period of time determined in the configuration (time-to-live) of each domain-name record.
Because they can answer questions more quickly, they also increase the performance of end-user applications that use the DNS.
To do this the name server queries each authoritative name-server in turn, starting from the DNS root zone.
It continues until it reaches the authoritative server for the zone that contains the queried domain name.
In addition, many home-networking routers implement caching resolvers to improve efficiency in the local network.
Some systems utilize nscd, which stands for the "name service caching daemon".