Editing Domain Name System (section)

====Recursive and caching name server====
In theory, authoritative name servers are sufficient for the operation of the Internet. However, with only authoritative name servers operating, every DNS query must start with recursive queries at the [[DNS root zone|root zone]] of the Domain Name System and each user system would have to implement resolver software capable of recursive operation.<ref>{{Cite web |title=DNS zone |url=https://www.ionos.co.uk/digitalguide/server/know-how/dns-zone/ |access-date=2022-03-31 |website=IONOS Digitalguide |date=27 January 2022 |language=en}}</ref>

To improve efficiency, reduce DNS traffic across the Internet, and increase performance in end-user applications, the Domain Name System supports DNS cache servers which store DNS query results for a period of time determined in the configuration (''[[time-to-live]]'') of the domain name record in question.
Typically, such caching DNS servers also implement the recursive algorithm necessary to resolve a given name starting with the DNS root through to the authoritative name servers of the queried domain. With this function implemented in the name server, user applications gain efficiency in design and operation.

The combination of DNS caching and recursive functions in a name server is not mandatory; the functions can be implemented independently in servers for special purposes.

[[Internet service providers]]  typically provide recursive and caching name servers for their customers. In addition, many home networking routers implement DNS caches and recursion to improve efficiency in the local network.