Nameserver lookup
List a domain's NS records and check the delegation agrees.
A nameserver lookup retrieves the NS records that declare which servers are authoritative for a domain's DNS. The tool lists those nameservers and helps you confirm the delegation at the registry matches what the authoritative servers report, since mismatches cause intermittent resolution failures. A consistent, redundant set of nameservers is a sign of healthy, resilient DNS. Because an unexpected change here can indicate a misconfiguration or even a hijack, SJ Monitor's DNS monitoring can watch the NS records and alert you to any change.
Frequently asked questions
How many nameservers should a domain have?
At least two for redundancy is standard, and many domains use four or more across diverse networks. Multiple nameservers keep resolution working if one fails.
What causes a nameserver mismatch?
A delegation mismatch happens when the NS records at the registry differ from those on the authoritative servers, often after a migration. It can cause intermittent failures until reconciled.
Can changes to my nameservers be detected automatically?
Yes. SJ Monitor's DNS monitoring continuously checks your NS records and alerts you immediately if they change unexpectedly.
What's the difference between authoritative and parent NS records?
The parent (registry) NS records control the delegation, while the authoritative NS records live in your own zone. They should match; a mismatch is a "lame delegation" that causes intermittent failures.
Should my nameservers be on different networks?
Ideally yes. Spreading nameservers across diverse networks or providers means a single network outage or DDoS won't take all of your DNS down at once.
What happens when I change nameservers?
Updating NS records at your registrar can take time to propagate (governed by the parent zone's TTL), and you should keep the old DNS host serving records until the switch fully rolls out to avoid resolution gaps.
More DNS tools tools
Want this checked automatically and around the clock? Create a free SJ Monitor account and we'll alert you the moment something changes.