SOA Record Lookup
Query the SOA (Start of Authority) record for a domain. View the authoritative name server, serial number, and zone parameters.
What is a SOA (Start of Authority) record?
The SOA record is a mandatory DNS record that identifies the authoritative name server for a zone and defines administrative parameters for the zone. Every domain has exactly one SOA record.
The SOA record contains values that govern secondary name server behavior — zone transfers, cache validity, and retry timing on failure.
Understanding SOA record fields
MNAME
The hostname of the primary authoritative name server for the zone. This is where zone update queries are sent.
RNAME
The zone administrator's email address. The first dot replaces @; e.g., admin.example.com → admin@example.com.
SERIAL
An incrementing number representing the zone version. Secondary servers perform a zone transfer when this value changes. Usually in YYYYMMDDNN format.
REFRESH / RETRY / EXPIRE
How often secondary servers check the SOA (REFRESH), when they retry on failure (RETRY), and when they consider the zone invalid (EXPIRE). All values are in seconds.
Frequently asked questions
Secondary DNS servers watch for an increasing serial number to trigger zone synchronization. Without an update, secondary servers may not pick up new records.
The first dot corresponds to the @ character. hostmaster.example.com means hostmaster@example.com.
Typical values: REFRESH 3600–86400 s, RETRY 900–3600 s, EXPIRE 604800 s (7 days), MINIMUM TTL 300–3600 s. Modern providers manage these values automatically.
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