Name server check
Looks up the NS set and the IPv4 and IPv6 addresses of up to eight name servers, and reports a single server, servers that do not resolve, all addresses in one /24 or /48, one top-level domain for all names, and servers inside the zone that need glue. The servers themselves are not contacted.
Updated 2026-10-27
What this tool checks
The NS set is asked for through public resolvers, then the IPv4 and IPv6 addresses of up to eight name servers:
- Count: a single name server.
- Resolution: a name server whose name has no address (
NS_UNRESOLVABLE). - Diversity: all addresses in one /24 (IPv4) and one /48 (IPv6), and all names under one top-level domain.
- Glue: name servers inside the zone.
How to read the result
Each name server is listed with its addresses. Diversity is judged from the addresses alone; two providers can share a network, and one provider can span several.
Limitations
- Network diversity is a heuristic from the address prefixes; operator and ASN are not looked up.
- At most eight name servers are resolved.
Use it from code
API reference for Name server check
curl -i "https://api.lookproof.dev/v1/dns/ns?domain=example.com"A request without payment is answered with 402 Payment Required and the exact price. See the API reference.
Limits
| Input | Domain |
|---|---|
| Deadline | 10 seconds |
| Freshness | Up to 5 minutes, never longer than the record TTL |
| Price | $0.01 per check |
Findings this tool can report
Name servers (6)
- Info
NS_IN_BAILIWICKA name server lies inside the zone it serves and needs glue records. - Warning
NS_NOT_FOUNDThe name has no NS records. - Warning
NS_SAME_NETWORKAll name servers are in the same network. - Warning
NS_SINGLEThe zone has only one name server. - Info
NS_SINGLE_TLDAll name servers are under the same top-level domain. - Warning
NS_UNRESOLVABLEA name server's name has no IPv4 or IPv6 address.
Check (1)
- Warning
CHECK_QUERY_BUDGET_EXCEEDEDThe check stopped after reaching its DNS query limit.
DNS (3)
- Error
DNS_DOMAIN_NOT_FOUNDThe DNS resolver reported that the domain does not exist. - Warning
DNS_RESOLVER_FAILUREThe DNS resolver returned a server failure. - Warning
DNS_RESOLVER_TIMEOUTThe DNS resolver did not answer in time.
Frequently asked questions
How many name servers should a zone have?
At least two, in different networks (RFC 1034 and RFC 2182). With one server, or several in one /24, a single failure takes the whole domain offline: NS_SINGLE and NS_SAME_NETWORK.
What does in-bailiwick mean?
A name server such as ns1.example.com that lies inside the zone it serves. It can only be found through glue records at the parent zone, which your registrar publishes. NS_IN_BAILIWICK reminds you to keep the glue in step.
Does the tool query the name servers directly?
No. Everything goes through public resolvers, so lame delegations (a server that does not answer for the zone) and differences between the parent's and the zone's NS sets are not detected.