Domain Name System

The main Internet operations database, which is distributed over a collection of servers and used by client software for purposes such as (a) translating a domain name-style host name into an IP address (e.g., "rosslyn.bbn.com" translates to "192.1.7.10") and (b) locating a host that accepts mail for a given mailbox address. (RFC 1034) (See: domain name.)

Tutorial: The DNS has three major components:

• Domain name space and resource records: Specifications for the tree-structured domain name space, and data associated with the names.
• Name servers: Programs that hold information about a subset of the tree's structure and data holdings, and also hold pointers to other name servers that can provide information from any part of the tree.
• Resolvers: Programs that extract information from name servers in response to client requests; typically, system routines directly accessible to user programs.

Extensions to the DNS [R4033, R4034, R4035] support (a) key distribution for public keys needed for the DNS and for other protocols, (b) data origin authentication service and data

integrity service for resource records, (c) data origin authentication service for transactions between resolvers and servers, and (d) access control of records.