what is a nameserver
A name server is a computer hardware or software server that implements a network service for providing responses to queries against a directory service.It translates an often humanly-meaningful, text-based identifier to a system-internal, often numeric identification or addressing component. name server indicates that its response is authoritative by setting the Authoritative Answer (AA) bit in the response to a query on a name for which it is authoritative. Name servers providing answers for which they are not authoritative (for example, name servers for parent zones) do not set the AA bit.