Nameserver & Zone Health
A health check of the servers that answer for your domain and of the zone's records. It queries every one of your nameservers directly: are they reachable, do they answer authoritatively, do they support IPv6, TCP and EDNS, and do they all agree on the same zone (SOA serial)? It also checks the SOA timers and validates your records — flagging too-low or mixed TTLs, duplicates, MX pointing at a CNAME, and NS/MX pointing at an IP literal.
Reviewed by the SysGlass team · Updated July 21, 2026
What it checks
- Each nameserver: resolves, answers authoritatively, IPv6 / TCP / EDNS support
- At least 2 nameservers, ideally on different networks
- All nameservers agree on the same SOA serial (no split-brain)
- SOA timers (refresh / retry / expire / minimum) are within sane ranges
- Record TTL hygiene: not too low or too high, consistent per RRset
- RFC violations: MX→CNAME, NS/MX pointing at an IP, duplicate records
How to read the result
- A single nameserver, or all on one network, is a resilience risk — one outage takes the domain offline.
- Different SOA serials across nameservers means a zone-transfer/sync problem.
- Very low TTLs add query load and latency; very high TTLs slow down changes and failover.
- MX or NS pointing at a CNAME or a bare IP violates the DNS specs and can break mail/resolution.
Frequently asked questions
Why should I have more than one nameserver?
DNS requires at least two, and best practice is to put them on different networks/providers, so a single outage doesn't make your whole domain unresolvable.
What TTL should my records use?
Commonly 300s–3600s for records you might change, longer for stable ones. Extremely low TTLs (<30s) add load and latency; very high TTLs make changes and failover slow to take effect.
Why is MX or NS pointing to a CNAME a problem?
The DNS specs forbid it — an MX or NS target must be a hostname with its own A/AAAA records, not an alias. Some resolvers and mail servers break on it.
Do my nameservers need IPv6?
It's recommended. IPv6-only resolvers should be able to reach your nameservers, and many large networks prefer IPv6 for DNS.