A and AAAA: address records

An A record maps a hostname to an IPv4 address and an AAAA record maps it to IPv6. Use them for web servers and other endpoints, but check that every published address is reachable and intended. A broken AAAA can affect only part of your visitors.

CNAME: an alias, not a redirect

A CNAME makes one hostname an alias of another hostname. DNS follows the alias before returning address records. It does not redirect a browser URL, and a normal CNAME cannot usually coexist with other record types at the same name.

MX: mail routing

MX records identify the hostnames that receive mail and assign priorities; lower values are preferred. Each MX target must resolve to A or AAAA records and should not be an IP literal or a CNAME. An MX record alone does not prove the mail service is accepting messages.

TXT: policies and verification

TXT records carry SPF, DKIM-related public keys, DMARC policies, domain verification tokens and other text data. Keep separate values clear, publish only one effective SPF record and verify that long values are stored exactly as the provider requires.

NS and SOA: authority and zone metadata

NS records delegate a domain or subdomain to authoritative nameservers. SOA contains the zone serial, responsible party and timing values used by DNS systems. Parent delegation and child NS records should be consistent.

CAA: certificate issuance policy

CAA lets a domain owner state which certificate authorities may issue certificates. Check issue and issuewild separately when using wildcard certificates, and remember that CAA controls issuance rather than ordinary browser access.

A safe record-change workflow

Record the old value and TTL, confirm the hostname and record type, make one change, query from more than one resolver, check the dependent website or mail service and wait for caches before making another change.

Common conflicts

Do not add a CNAME beside A or MX at the same name, publish multiple SPF records, put an IP in an MX field, or assume DNS changes instantly replace every cached answer.

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