What are DNS Records?

DNS (Domain Name System) records are the entries in a DNS database that map domain names to IP addresses and other information about a domain. These records are used by DNS servers to resolve domain names to IP addresses, allowing users to access websites and other resources using human-readable domain names instead of IP addresses. There are several different types of DNS records, including A records, MX records, CNAME records, and NS records, each of which serves a specific purpose.

Information you can expect to be stored in DNS records includes: an associated IP address, domain name, time to live (TTL), class (most commonly IN, meaning internet), and type (e.g. A, AAAA, etc.).

An example of how this can appear is as follows:

IP Address	181.151.30.123
Domain Name	aoitcloud.com
TTL	3600
Class	IN
Type	A

DNS Record Types

There are a variety of different DNS record types that you should be aware of when considering utilising a DNS server. The following is a brief description of each type.

A Record (Address)

This type is most commonly used to map a fully qualified domain name (FQDN) to an IPv4 address, converting domain names to their relevant IP addresses.

• AAAA Record (Quad A)
  These records are similar to A records, but map to IPv6 addresses rather than IPv4. As IPv6 adoption grows and the pool of available IPv4 addresses keeps shrinking, having AAAA records in place future-proofs your domain for IPv6-only visitors and networks.
  
• CNAME Record (Canonical Name)
  This record acts as an alias which points to another domain or subdomain, rather than to an IP address directly. This type of alias mapping (FQDN to FQDN) lets you direct multiple hostnames to a single location. If you need to change an IP address over time, this record type lets you make that change without affecting user bookmarks, links, or other references.

ALIAS / ANAME Record

This record type can be used in place of a CNAME, the key difference being that it allows you to point the root of your domain (e.g. aoitcloud.com rather than www.aoitcloud.com) to a hostname or FQDN – something a standard CNAME record isn’t allowed to do at the domain root.

• SOA Record (Start of Authority)
  This type stores information about a domain and is used to direct how a DNS zone propagates to secondary name servers.
  
• NS Record (Name Server)

This type of record specifies which name servers are authoritative for a domain or subdomains. However, these records should not be pointed to a CNAME record type.

• MX Record (Mail eXchange)

A Mail eXchange record specifies which mail servers handle email delivery for a domain. This type needs to point to a mail server hostname, not to an IP address.

• TXT (text) Record

This type of record allows administrators to add human and machine-readable notes, and is used for things such as email validation (SPF, DKIM, DMARC), site and ownership verification, and other domain-level policies. Unlike most record types, a TXT record can hold arbitrary text – but many of its common uses (SPF, DKIM, DMARC) do require a specific, strict syntax within that text, so check the relevant format carefully before publishing one.

• SRV Record (service)

This record type allows services such as instant messaging or voice over IP (VoIP) to be directed to a separate host and port location.

• PTR Record (pointer)

This is the reverse of an A or AAAA record – it maps an IP address back to a domain name. PTR records live in special reverse-lookup zones (managed by whoever controls that IP range), separate from your domain’s own forward-lookup zone.

A final tip to consider when setting up your DNS records is to check for typos and mistakes when entering record information. IP addresses in particular are essential to get exactly right. Your DNS provider’s zone editor is a good place to check your work and identify any mistyped information.