Why does the admin email get rewritten with a dot instead of an @?

The SOA record's RNAME field uses a dot in place of the @ sign in DNS master file syntax specifically because @ is a reserved character meaning "current zone origin" in zone files, so admin@example.com becomes admin.example.com. Any literal dot already in the local part of the email is escaped with a backslash, since an unescaped dot would otherwise be read as a label separator.

What do refresh, retry, and expire actually control?

These fields govern secondary (slave) nameserver behavior: refresh is how often a secondary checks the primary for a new serial number, retry is how long it waits before retrying after a failed check, and expire is how long a secondary keeps serving the zone from its cache if it can't reach the primary at all before considering its data stale and stopping.

Do I need to increment the serial number myself?

Yes. This tool doesn't track prior serial values, so you need to increase the serial number on every zone edit yourself (a common convention is YYYYMMDDnn, the date plus a two-digit revision counter) or secondaries won't detect the update and won't pull the new zone data.

Why does an MX record need a priority but other types don't?

MX records specifically support multiple mail exchangers for the same domain with an explicit preference order, so a lower-numbered priority is tried first; other record types in this generator (A, AAAA, CNAME, TXT, NS) don't have an equivalent preference mechanism in the DNS protocol.

DNS Zone File Generator - BIND-Style Zone File Builder

Overview

Introduction

Hand-writing a BIND zone file means getting the SOA record's parenthesized field order right, remembering to trail fully-qualified names with a dot, and correctly formatting the admin email's dot-for-@ substitution, all easy details to get subtly wrong.

This tool builds the file from clearly labeled fields instead, entirely in your browser.

What Is DNS Zone File Generator?

A BIND-style DNS zone file generator that produces the $ORIGIN/$TTL header, a fully formatted SOA record, and one line per resource record you add.

It's part of this site's DNS & Domain Tools collection and supports the six most common record types: A, AAAA, CNAME, MX, TXT, and NS.

How DNS Zone File Generator Works

The zone origin and TTL become the file's $ORIGIN and $TTL directives; the primary nameserver, admin email, and five numeric SOA fields (serial, refresh, retry, expire, minimum) are assembled into the standard parenthesized SOA record format that BIND expects.

Each resource record row is validated for its type (MX rows require a numeric priority) and rendered as a tab-separated name/class/type/value line, in the order you added them.

When To Use DNS Zone File Generator

Use it when standing up a new authoritative zone for a domain and you want a correctly structured starting zone file rather than hand-assembling one from a template.

It's also useful for double-checking the SOA field order and admin-email escaping rules when reviewing an existing zone file someone else wrote.

Features

Advantages

Produces the SOA record's fields in the correct order with the admin email correctly converted from @ to dot notation automatically.
Supports the six record types that cover the overwhelming majority of real zone files in one form.
Requires all SOA numeric fields to be entered explicitly, avoiding an accidentally-omitted field that would otherwise break the record.

Limitations

Doesn't support less common record types like SRV, CAA, or DNSSEC-related records (DNSKEY, DS, RRSIG); only A/AAAA/CNAME/MX/TXT/NS are covered.
Doesn't validate that record values are semantically correct (e.g. that an A record's value is actually a valid IPv4 address) beyond requiring the field isn't empty.
Doesn't track or auto-increment the serial number between edits; you supply and manage it yourself.

Examples

A minimal zone with an apex A record and a mail exchanger

Input

origin: example.com, ttl: 3600, primaryNs: ns1.example.com, adminEmail: admin@example.com, serial: 2026072601, refresh: 3600, retry: 900, expire: 1209600, minimum: 3600, records: [{type: A, name: @, value: 203.0.113.10}, {type: MX, name: @, value: mail.example.com, priority: 10}]

Output

$ORIGIN example.com.
$TTL 3600

@   IN  SOA   ns1.example.com. admin.example.com. (
        2026072601      ; serial
        3600      ; refresh
        900      ; retry
        1209600      ; expire
        3600 )    ; minimum

@	IN	A	203.0.113.10
@	IN	MX	10	mail.example.com

The @ name refers to the zone apex (example.com itself); the MX record includes its priority (10) before the mail server hostname.

Best Practices & Notes

Best Practices

Increment the serial number on every edit, using a consistent convention like YYYYMMDDnn, so secondary nameservers reliably detect and pull the update.
Set expire meaningfully longer than refresh and retry combined, so a secondary doesn't stop serving the zone during a brief primary outage.
Terminate any manually-added fully-qualified name with a trailing dot; a name without one is interpreted as relative to $ORIGIN, which is a common source of subtly broken zone files.

Developer Notes

The admin email's local part has any literal dot escaped with a backslash before the @ is replaced with a dot, matching RFC 1035's master file syntax for the SOA RNAME field, since an unescaped dot in that position would otherwise be parsed as an additional label boundary rather than part of the local part.

DNS Zone File Generator Use Cases

Generating a starting zone file when provisioning a new authoritative DNS zone
Producing a consistent SOA record and record set for a documentation example or internal runbook
Reviewing the correct SOA field order and email-escaping convention against a real, generated example

Common Mistakes

Forgetting to increment the serial number after editing a zone, so secondary nameservers never notice the change and continue serving stale data.
Leaving off the trailing dot on a fully-qualified nameserver or mail server hostname, causing it to be silently interpreted relative to the zone origin instead.

Tips

Use the MX Record Lookup tool afterward to confirm a live zone's MX records actually match what you intended to publish.

DNS Zone File Generator