Topic
Domain Name System (DNS)
DNS is the distributed naming system that lets internet applications look up records associated with domain names.
At a glance
- Common address records
- A and AAAA
- Authority records
- NS
Overview
The Domain Name System is a distributed database used to publish information about names on the internet. A lookup can return an address for a website, the servers responsible for receiving email, authoritative name servers, verification records, and other data. DNS is therefore a general naming and discovery layer rather than a directory that only maps websites to IP addresses.
How a lookup works
A client usually asks a recursive resolver for a record. The resolver can use cached information or query the DNS hierarchy until it reaches an authoritative source for the requested name, then returns the result for the client to use according to the record type and its remaining cache lifetime.
Records have different jobs
A and AAAA records provide network addresses, MX records identify mail exchange servers, NS records identify authoritative name servers, and TXT records can carry text used for verification or policy. Changing one record type should not be assumed to change unrelated services.
Sources and review
MOOR's explanatory text is supported by the following source links.
- Domain Name System — ICANN
- Domain Names - Concepts and Facilities — RFC Editor