Any record type for any name, with the answer's status explained.
DNS translates names into the addresses and settings that make a website, a mail system or a login work. When any of them break, the first question is what a name actually publishes.
Pick a record type, or all of the common ones, and see the answer with its TTL. The result tells you whether an empty answer means the name does not exist, exists with no record of that type, or that the resolver failed (often a nameserver outage or a DNSSEC problem). Enter an IP address for a reverse lookup.
Resolvers cache the old answer for as long as its TTL. Lower the TTL a day before a planned change, and expect old answers until the previous TTL has passed.
The reverse of an address record: it maps an IP address back to a name. Mail servers should have one that matches.
A public recursive resolver, asked from our servers. Names that resolve only inside a private network, and private address ranges, are not looked up.