DNS Storage

Updated Jan 16, 2018 ·

Overview

DNS servers need a way to store information so they can respond to queries. This data is organized in zones and structured as resource records.

DNS Zones

DNS servers organize their data into zones so they can respond to queries efficiently.

• Forward lookup zones map domain names to IP addresses
• Reverse lookup zones map IP addresses back to domain names

Zones allow DNS to handle both normal and reverse queries consistently across the network.

Resource Records (RRs)

Resource records are the building blocks of DNS zones. They store all the necessary information for a domain or IP.

• Each record stores specific data about a domain or IP
• Examples include A records for IPv4 and AAAA records for IPv6

Common Record Fields/Format:

Field	Description
Name	The domain or IP the record refers to
Type	Specifies the record type (e.g., A=1, NS=2)
Class	Usually IN for Internet
TTL	Time the record stays cached
Data Length	Size of the resource data
Resource Data	The actual information stored

info

Zones and resource records are the backbone of DNS, which allows resolvers to retrieve both forward and reverse mappings efficiently.

Resource Record Types

DNS uses different types of resource records (RRs) to store information about domains and IP addresses. Each type serves a specific purpose in resolving names or providing additional data.

Record Type	Purpose	Example
A	Maps a domain to an IPv4 address	example.com → 93.184.216.34
AAAA	Maps a domain to an IPv6 address	example.com → 2606:2800:220:1:248:1893:25c8:1946
CNAME	Aliases one domain to another	www.example.com → example.com
MX	Mail exchange server for email	example.com → mail.example.com
NS	Authoritative name server for the domain	example.com → ns1.example.net
PTR	Maps an IP address back to a domain (reverse lookup)	93.184.216.34 → example.com
TXT	Stores arbitrary text data	SPF record for email verification

For more information, please see Resource Records.