DNS record types explained

Every interaction with the Internet - whether visiting a Web site, sending an e-mail or verifying your domain - depends on the proper configuration of DNS records. But what exactly do they do? And what goes wrong when they are set incorrectly? You can read about it here.

Basic records for domain routing

• AA record
• AAAA record
• CNAME record

The most fundamental DNS records are the A and AAAA records. These ensure that a domain name is translated to an IP address. The A record points to an IPv4 address, the AAAA record to an IPv6 address. Without these records, a browser or application does not know where to find the server. This is essential for proper loading of Web sites and other Web applications.

There is also the CNAME record, which redirects a domain name to another domain name. This is often used for subdomains such as app.ctrldns.co.uk, which you want to link to an external service. Note that a CNAME should never be on the root domain - this is a common mistake that can cause inaccessibility.

E-mail related records

• MX record
• TXT record

For e-mail traffic, the right MX-records are indispensable. These indicate which mail servers are authorized to receive e-mail for your domain. Incorrectly set MX records cause incoming e-mail not to arrive, or senders to receive error messages.

In addition, there are TXT records that are often used for e-mail verification, for example, SPF (which servers are allowed to send mail on behalf of your domain), DKIM (digital signing of outgoing mail) and DMARC (policy for handling unverified e-mail). TXT records are also used for domain validation by external parties, such as Google or Microsoft.

Technical and infrastructure records

• NS-record
• SOA record
• SRV record
• PTR record

NS records indicate which nameservers have authority over your domain. If they are set incorrectly, the entire DNS zone will not function. This often occurs during migrations to another provider or confusion between registrars and hosting parties.

The Start of Authority (SOA) record contains metadata about the zone, including the primary nameserver address and DNS replication settings. In practice, you rarely need to modify this record, but it must be correct for propagation between nameservers to work properly.

SRV records are used for specific services such as VoIP, chat or Microsoft 365. They indicate where a particular service is running and which ports are used. These records are technical and error-prone - even a small change can cause service interruptions.

PTR records are reverse DNS records that translate an IP address to a domain name. They are used for reverse DNS, especially with email servers and for certain security checks. They are usually not in your own zone file but with the IP range administrator.

These are the DNS records we often use. There are more, check them out at: iana .org