Online Tool Store
Zone File Validator
Paste a DNS zone file and get line-by-line syntax checks for SOA, NS, A, AAAA, MX, CNAME, and TXT records, with errors and warnings flagged instantly in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
How the Zone File Validator works
- Paste a BIND-style DNS zone file, including any $ORIGIN and $TTL directives.
- Click Validate to scan every line for its record type and check the fields that type requires.
- Review line-numbered errors and warnings, then download the report as a text file if you need it.
What gets flagged
Errors cover things that will break a zone load: an A record with a malformed IPv4 address, an MX record missing its numeric priority, or an SOA record with too few fields. Warnings cover softer issues, like a missing $ORIGIN directive or a TXT value that is not wrapped in quotes.
FAQ
Which record types does this check?
SOA, NS, A, AAAA, MX, CNAME, TXT, PTR, SRV, and CAA. Each type is checked against its expected field layout, such as an IPv4 address for A records or a priority and hostname for MX records.
Does this replace a real DNS server test like named-checkzone?
No. This is a fast, offline sanity check for obvious syntax mistakes before you deploy — bad IP formats, missing SOA fields, unquoted TXT values. A real nameserver or named-checkzone still has the final say on whether a zone loads.
Is my zone file uploaded anywhere?
No. The text you paste is parsed and checked entirely in your browser with plain JavaScript regular expressions — nothing is sent to a server.
How we compare
| Feature | Online Tool Store | named-checkzone | Manual review |
|---|---|---|---|
| No install required | ✓ | ✗ | ✓ |
| Line-numbered results | ✓ | ✓ | Manual work |
| Authoritative zone-load verdict | ✗ | ✓ | ✗ |
Use this to catch obvious mistakes before a deploy; use named-checkzone or your DNS provider's own validation as the final check before a zone goes live.