b2KIT

Nameserver Lookup

Identify authoritative nameservers for a domain and check NS record configuration and delegation.

Tested tool guide Tested browser tools Checked August 16, 2026

What Nameserver Lookup does and how it behaves

Nameserver Lookup answers two related DNS questions for the domain you enter: which NS hostnames are published for it, and whether the parent delegation agrees with the zone's own NS records. It helps trace DNS authority and identify an incomplete nameserver migration. Enter a DNS name, not a full URL containing a scheme, path, or query string. The common mistake is treating an NS hostname as the website host. It identifies DNS authority only; web and mail services can run elsewhere.

How the result is produced

1

NS records and delegation

The lookup retrieves the domain's NS resource record set, whose values are DNS hostnames designated to serve the zone. It also examines the delegation published by the parent zone when one exists. This separates the nameservers toward which the parent directs resolvers from the nameservers that the child zone declares for itself.

2

Configuration comparison

The configuration check compares the parent-side delegation with the zone's authoritative NS set. Missing or additional names identify a difference worth investigating. NS records have no numerical preference, so their displayed order is not a routing priority. Capitalization and a final root dot are DNS presentation details, not separate nameserver identities.

Good uses

  • Confirm that a registrar nameserver change has reached the parent delegation and that the new zone advertises the intended NS set before the old DNS service is retired.
  • Investigate intermittent SERVFAIL responses or inconsistent DNS answers after a migration by checking whether the parent and child still name different authoritative servers.
  • Validate a delegated subdomain, such as api.example.com, before another team or provider takes responsibility for serving that part of the DNS namespace.

Limits and checks

  • Matching parent and child NS names do not prove availability. A listed server can be unreachable, refuse the zone, carry an older serial, or answer differently from its peers.
  • A recent delegation change may not appear uniformly while recursive resolvers retain previously cached DNS data. Two observers can therefore receive different but formerly valid NS sets during a transition.
  • The result identifies authoritative DNS hostnames, not the machines delivering the website or email. A nameserver's brand also does not reliably establish the domain owner or registrar.

Common questions

Why does the parent delegation differ from the zone's NS records?

The two sets are published in different places. The parent zone holds the delegation used to reach the child, while the child publishes its own NS RRset. They can diverge during a migration, after an incomplete registrar update, or because an authoritative server has stale zone data. Persistent disagreement deserves investigation even when some lookups still succeed.

Does a nameserver result show where the website is hosted?

No. An NS result identifies the servers authoritative for DNS data. Those servers may belong to a managed DNS company, registrar, hosting company, or the domain owner. It does not reveal the origin web server. Check A, AAAA, and CNAME records separately, remembering that proxies and content delivery networks can conceal the origin.

References and verification

The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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