Help / Nameserver check
Nameserver check
Queries a domain’s own nameservers directly (not a resolver cache) to check the delegation, glue records, SOA serial sync and lame servers.
How to use it
- Type a domain (a subdomain works; it finds the zone).
- Press Check. Each nameserver is asked over TCP port 53 with recursion off.
Reading the results
- Delegation
- The nameserver list the parent zone (like .com) hands out for your domain.
- Glue
- Addresses the parent provides for nameservers inside your own domain, so they can be found.
- Authoritative (AA)
- The server says it holds the real data for the zone.
- Lame
- Listed as a nameserver but not authoritative: a misconfiguration.
- SOA serial
- The zone’s version number. All servers from one provider should match.
Examples
- github.com Two providers (NS1 + Route 53)
- wikipedia.org Single provider
From the command line
curl "https://tools.nexayori.com/authoritative?q=github.com" curl "https://tools.nexayori.com/authoritative?q=github.com&format=json"
| q | Domain |
| format | text, json or html |
Questions
Why are serials different between my providers?
Multi-provider setups each keep their own SOA (Route 53 always says 1). Serials are only compared within one provider.
My Cloudflare nameservers say “Not testable here”.
This tool runs on Cloudflare, which doesn’t allow connections to its own servers. Other checks still apply.
Limitations
- Only IPv4 addresses of nameservers are queried.
- Nameservers hosted on Cloudflare can’t be queried directly.
- Up to 8 nameservers.