DNS record types explained

The records you will see most often

A records map a hostname to an IPv4 address. AAAA records do the same for IPv6. These are the records most directly associated with reaching a server.

CNAME records make one hostname an alias of another hostname. The resolver follows the target name and then resolves that name to its final records.

Mail and verification records

MX records say which mail servers receive email for a domain and include a preference value. Lower values are tried before higher ones.

TXT records carry arbitrary text and are widely used for domain verification and email authentication. SPF and DMARC are both published through TXT records, while DKIM commonly publishes keys beneath a selector-specific hostname.

Delegation and certificate policy

NS records identify nameservers responsible for a DNS zone. SOA contains zone-management information such as the primary nameserver, serial number and timing values.

CAA records let a domain publish which certificate authorities are authorised to issue certificates for it. They do not replace certificate validation; they provide issuance policy to participating certificate authorities.

PTR and reverse DNS

PTR records are used by reverse DNS. Instead of resolving a hostname to an address, they associate an IP address with a hostname through the reverse-DNS namespace.

Which record should you check?

1. Website not reaching the right server: A, AAAA and CNAME.
2. Email not arriving: MX, then related SPF/DKIM/DMARC TXT records.
3. Nameserver migration: NS and SOA.
4. Certificate issuance problem: CAA.
5. IP-to-hostname check: PTR through reverse DNS.
6. Recent DNS change: inspect the record itself, then compare resolver caches and TTLs.