DNS Defined - Glossary


A wide-area network created in 1969 by the Advanced Projects Research Agency (ARPA), in tandem with universities and research centers to investigate the utility of high-speed data communication for scientific collaboration and military operations. ARPANET provided the basis for development of the Internet's protocol suite; roughly, the 100 standards that pertain to the Internet.

Berkeley Internet Name Domain (BIND)
Standard implementation of DNS based on UNIX systems.

boot file
File that points the name server to the database files of resource records.

caching server
Name server that caches name data but is not authoritative for a domain.

Name server that gets its authority from a parent server.

Defense Advanced Projects Research Agency. Formerly the Advanced Projects Research Agency (ARPA).

Process of reassigning authority for a subdomain or zone to ensure decentralized administration.

Subdivision of the Internet corresponding to a group of hosts on a network with a common administration.

domain name
Name corresponding to a domain, organized hierarchically. A domain name is fully qualified when it includes the top level domain and an ending dot.

domain name server
Host in the domain that is the name authority for the zone.

Domain Name System (DNS)
Distributed system used to define names for Internet hosts.

Host on a network that prevents other hosts on that network from “getting out” as well as external hosts from “getting in.”

forwarder and forwarding server
A forwarder is a target server for a forwarding server that acts as a slave server.

Network formed by connecting dissimilar hosts and networks with TCP/IP protocols. When capitalized, this term refers to network created by DARPA that forms the backbone of internet research.

inverse query
Process of getting a domain name from a database based on another search factor.

iterative querying
Process used, most often by name servers, to request a referral to another server if not able to answer a query.

leaf domain
Domain on the lowest hierarchic level in the domain name system; usually an individual host machine.

Name server from which subzone servers obtain authority.

primary master server
Name server with authority over a zone.

protocol group (or class)
Field in a resource record. The value is usually IN for the Internet protocol group but can also include CH for CHAOS and HS for Hesiod.

recursive querying
Process used, most often by resolvers, to pass the DNS query to another server if not able to answer it.

request for comments (RFC)
Working notes of the Internet research and development community.

Client routine that queries a name server, interprets the responses, and returns the data to the requesting program. A stub resolver, which doesn't build a local cache, is the most common type.

resource records
Records containing the data associated with domain names

reverse mapping
Process of finding a domain name based on an IP address

root name server
Ultimate Internet naming authority

secondary master server
Backup server for a primary master

slave server
Name server that depends solely on forwarding servers for authoritative data.

Start of Authority (SOA) record
Usually the first resource record in a name server database that establishes the authority for the zone.

Domain on a lower hierarchic level in the domain name system.

time to live (TTL)
Field in a resource record that specifies how long a domain resolver should cache the record before discarding the cached data and proceeding to query a name server for it.

All or part of a domain under a common delegation. Consequently, zone data is the data for a particular zone.