What types of DNS records are there and what are they used for?

In this third and final instalment of our DNS series, we are going to look at some common DNS records and what their purposes are in domain name resolution.

You may find this information useful when you need to update or add DNS records yourself via your domain provider’s domain manager.

So what are DNS records?

Well, literally they’re just formatted text files that form what is called a zone file or zone. Zones are made up of your zone records which contain mappings between IP addresses and domain names or mappings between other resources.

Below are the most common DNS records and their purpose in relation to DNS resolution.

1. SOA – The Start of Authority record holds basic administration information about the zone such as the primary nameserver of the zone, the email of the domain administrator, the domain serial number and refresh timers. SOA are usually added automatically by your domain provider and are mandatory and are not editable.
2. A record – This record maps or points the IPv4 IP address like 203.168.10.1, to a domain like example.com. You can have multiple A records pointing domain names to multiple IP addresses for redundancy purposes, or multiple domains could point to the same address. All A records are editable.
3. AAAA record – This record maps or points the IPv6 IP address like 2001:db8:0:1:1:1:1:10 to a domain like example.com. It has the same properties as an A record.
4. CNAME – A Canonical Name record is an alias record used to map one domain or subdomain to another, but you can’t map to an IP address. An typical example of a CNAMe is if you create a CNAME record www.example.com that points to an A record example.com. Note that you can’t have two CNAME records with the same name, and you can’t point one CNAME record to another CNAME record. All CNAME records are editable.
5. MX record – Mail Exchange records point or direct a domain’s emails to an email exchange server. For example you may set up an MX record for emails that are sent to @example.com, so that they are routed to mail.example.com, which is the mail exchange domain of a mail server. If you were using Outlook or Google as your mail server, this is where you would add their mail exchange domain. MX records are fully customizable and editable.
6. TXT record – These records can be anything from simple notes to machine-readable instructions that assist with domain verification and email exchange records. For instance, Google may ask you to add a TXT record such as “google-site-verification=6P08Ow5E-8Q0m6vQ7FMAqAYIDprkVV8fUf_7hZ4Qvc8” in order to verify ownership of your domain before you can access their services. TXT records are editable and can be added and deleted.
7. SRV – This record contains a name and port specifying a specific service location. An example would be if you were setting up VoIP, you would create an SRV record to point to the VoIP service. An example may include fields that might look something like _sip._tcp.example.com. 86400 IN SRV 0 5 5061 sipserver.example.com. however these fields may be arranged differently in your domain provider’s domain manager.
8. NS – A Nameserver record contains the name of the authoritative DNS nameserver with the actual DNS records. This record points a domain to the DNS Nameserver that holds the record and without it, no one would be able to load up a website or web application. This is a mandatory record that is editable.

There are many other DNS records that you may come across such as PTR, DNAME, CERT, IPSECKEY and DNSKEY, but primarily you’ll deal with the record types listed above.

That concludes our series on the workings of DNS.

I hope the information contained has helped broaden your understanding of the DNS system and provided some context around the DNS records that you may come across in your administration of your own domain names.

Hopefully now you will be better able to customize those records for your own specific requirements.