DNS record format checker

Check a small set of A, AAAA, CNAME, and MX records for common formatting mistakes and owner-name conflicts. This runs in your browser; it does not look up DNS or verify that a provider accepts the records.

Paste records

Enter one record per line as TYPE NAME VALUE. For MX, include priority before the mail server: MX @ 10 mail.example.com. Use @ for the zone apex. Blank lines and lines beginning with # are ignored.

Paste one or more records using the format above.

What the checker covers

• A: requires an IPv4 address.
• AAAA: requires an IPv6 address.
• CNAME: requires a DNS hostname target. A CNAME owner cannot also have another listed record type.
• MX: requires a whole-number priority from 0 to 65535 and a DNS hostname target. Multiple MX records for one owner are allowed.

Name checks allow ordinary ASCII hostname labels, a final dot, @, and a leading wildcard label. Internationalized names must be entered as ASCII-compatible punycode. Provider-specific features, DNSSEC records, aliases at the zone apex, and all other record types are outside this check. A clean result means only that these limited local checks passed.

Record type guide and examples

• A www 192.0.2.10 associates a name with an IPv4 address.
• AAAA www 2001:db8::10 associates a name with an IPv6 address.
• CNAME shop store.example.com aliases a name to another hostname.
• MX @ 10 mail.example.com directs mail for the zone to a mail host at the entered priority.

The addresses above use documentation ranges and are examples only, not live destinations. Check your DNS provider's own instructions before saving changes. Cloudflare's DNS record guide describes common record types and their roles (checked November 3, 2026). For cache timing, see the DNS TTL waiting-window estimator.