DNS Delegation, Serial & TTL Auditor: asking every nameserver separately

A domain usually has two or more nameservers, and a normal lookup asks whichever one answers first. That hides the interesting failures. This check asks a public resolver for the delegation, then puts the same three questions to every nameserver directly: which serial the zone carries, which nameservers the zone itself lists, and which address the domain resolves to. Answers that differ are the finding.

From this server: DNS queries only, to public resolvers and to the domain's own nameservers. No web page is fetched, no cookies are sent, nothing is stored beyond the counter entry: IP address, time and size of the request, for seven days.

Check delegation

Limits worth knowing: at most six nameservers are queried, over UDP, and an answer larger than 4 KB is truncated. A server behind a firewall that drops UDP from unknown addresses will look silent here even though it answers resolvers normally.