SOA Lookup
Fetch the Start of Authority record (primary NS, serial, timers).
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Enter a domain above and press Run to start the check.
About the SOA Lookup
SOA Lookup retrieves the Start of Authority record, the foundational record that defines administrative parameters for a DNS zone. It lists the primary authoritative nameserver, the responsible administrator's email, the serial number, and the refresh, retry, expire, and minimum TTL timers. These values govern how secondary nameservers synchronize the zone and how long negative responses are cached.
How to use
- Enter the domain whose zone you want to inspect.
- Run the lookup to fetch the SOA record.
- Review the serial number and timer values to verify zone configuration.
Frequently asked questions
- What is the SOA serial number for?
- The serial number versions the zone; secondary nameservers compare it to know when to pull updates. It should increase with every change to the zone.
- What do the refresh, retry, and expire timers do?
- Refresh sets how often secondaries check for updates, retry sets the wait after a failed check, and expire sets how long stale data stays usable before the zone is dropped.
- What is the minimum TTL field?
- In modern DNS the SOA minimum field defines the TTL for negative (NXDOMAIN) responses, controlling how long non-existence is cached.