About
The resolver is a program that queries a database names in response to client requests to determines:
- or vice versa. (DNS - rDNS - Reverse DNS (lookup|resolution) - from IP to name
They must be able to access at least one name server and use that name server's information to answer a query directly, or pursue the query using referrals to other name servers.
A resolver is typically directly accessible to user programs; hence no protocol is necessary between the resolver and the user program.