What zone file syntax does this support?

It follows the RFC 1035 master file format used by BIND. It handles $ORIGIN and $TTL directives, owner-name inheritance, the @ origin shorthand, semicolon comments, and multi-line records wrapped in parentheses such as SOA.

How are relative names resolved?

A name without a trailing dot is treated as relative and the current $ORIGIN is appended. A name ending in a dot is fully qualified and left unchanged. The @ symbol expands to the current origin.

How does TTL inheritance work?

If a record omits its TTL, the value from the most recent $TTL directive is used. The tool also converts TTL suffixes (s, m, h, d, w) into seconds so 1h30m becomes 5400.

Why is a record flagged as an error?

A record is flagged when its type is not a recognised DNS record type, or when a record that requires RDATA has none. Misplaced tokens usually mean a missing owner name or a stray comment character.

Is my zone file uploaded anywhere?

No. Parsing happens entirely in your browser using JavaScript. The zone file never leaves your device, which makes it safe for internal or sensitive DNS exports.

DNS Zone File Parser

A DNS zone file is the plain-text source of truth for a domain’s DNS records, written in the RFC 1035 master file format that BIND and most authoritative nameservers understand. When you export a zone from your DNS provider or migrate between hosts, it helps to see every record laid out cleanly with names, TTLs, and types resolved. This parser does exactly that in your browser.

How it works

The parser tokenizes the zone file the way a nameserver would when loading it:

Lines are pre-processed: semicolon comments are stripped (while respecting quoted strings), and records wrapped in parentheses — such as a multi-line SOA — are joined into a single logical line.
Directives $ORIGIN and $TTL update the current origin and default TTL.
For each record, if the line begins with whitespace the owner name is inherited from the previous record; otherwise the first token is the owner name. @ expands to the origin, and names without a trailing dot get the origin appended.
Optional TTL and class tokens (in either order) are detected, then the record type and remaining tokens become the RDATA.

TTL values such as 1h30m are normalized to seconds using the standard unit table (s, m, h, d, w).

Example

Given the directive $ORIGIN example.com. and the line:

www  IN  A  203.0.113.10

the parser resolves the owner name to www.example.com., class IN, type A, and RDATA 203.0.113.10. A blank-owner follow-up line inherits www automatically.

Notes

A successful parse confirms the file is syntactically well-formed — it does not query live DNS, so it will not tell you whether the records are actually published or propagated. Use it to audit exports, diff zones, or sanity-check hand-edited records before importing them.