Nameserver checks

DomainCare resolves your domain's NS records and then directly queries each listed nameserver to confirm it responds authoritatively. A nameserver that stops responding causes DNS resolution failures for anyone trying to reach your domain.

What it monitors

• NS record resolution — whether NS records exist for your domain at all
• Nameserver count — flags domains with fewer than 2 nameservers, since a single NS is a single point of failure
• Authoritative response — directly queries each nameserver by IP and asks it to resolve your domain's SOA record; a nameserver that does not respond authoritatively is flagged
• Majority availability — the check passes only when at least half of your listed nameservers respond authoritatively

How often it runs

The nameserver check runs every 6 hours (21,600 seconds). Each listed nameserver is queried in parallel — the total check time is bounded by the slowest responding nameserver rather than the sum of all query times.

The check resolves each nameserver hostname to an IP address (preferring IPv4, falling back to IPv6) before sending the authoritative query. If a nameserver hostname does not resolve to any IP, that nameserver is counted as non-authoritative.

Alerts this check produces

Event	Tone	When it fires
nameserver_not_authoritative	Warning	At least half of listed nameservers do not respond authoritatively to SOA queries
nameserver_count_low	Warning	Fewer than 2 nameservers are listed in the NS record set
nameserver_records_invalid	Failure	NS record resolution fails entirely — no nameservers found
nameserver_recovered	Recovery	A majority of nameservers are authoritative again after a previous failure event

What to do when alerts fire

• nameserver_records_invalid — no NS records. Your domain has no NS records, which means DNS resolution fails for the entire domain. Log in to your domain registrar and verify that nameserver delegation is configured. This often happens after a registrar transfer where the receiving registrar's nameservers were not set.

• nameserver_count_low — fewer than 2 NS records. Add a second nameserver through your DNS provider. Running a single nameserver means a single outage takes your entire domain offline. Most DNS providers include redundant nameservers at no extra cost.

• nameserver_not_authoritative. One or more listed nameservers are not responding with authority for your domain. Check with your DNS provider whether nameserver synchronization is complete. This can occur after migrating DNS providers when the old nameservers are still listed but have been deprovisioned, or when a secondary nameserver falls out of zone transfer sync.

• After making changes, DNS delegation changes can take up to 48 hours to propagate globally, though most resolvers see updates within a few hours. DomainCare will emit nameserver_recovered once a majority of nameservers respond authoritatively.

Related

• DNS checks
• Uptime checks