IPv4 Nameserver Monitor
A nameserver that only publishes an AAAA record is unreachable from any resolver still running IPv4-only. This check looks up the A record for every nameserver listed on the zone and reports the share that have IPv4 reachability.
What we check
We fetch the zone's NS records, then for each nameserver hostname we query its A records. A nameserver passes if it returned at least one A record.
Why it matters
IPv6 adoption is meaningful but far from universal — large swaths of consumer ISPs, corporate networks, and DNS resolver infrastructure still operate IPv4-only. A nameserver without an A record is invisible to those resolvers, which means part of the internet can't look up your zone.
Status outcomes
Every nameserver has at least one A record.
Some nameservers have A records and some don't. Resolution still works for IPv4-only resolvers as long as one nameserver answers, but you've lost redundancy.
None of the nameservers expose IPv4. The zone is unreachable from IPv4-only resolvers.
The zone has no NS records.
How to fix
Add an A record to the affected nameserver's hostname, or replace the nameserver in the zone's NS list with one that does have IPv4. If the nameserver belongs to a managed DNS provider, this is usually fixed by the provider — check whether you're pointed at the right NS hostnames.