WHOIS and DNS Lookup performs registry queries and DNS record lookups from an Android device. It covers WHOIS across public top level domains, reverse address lookups, and the common record types.
The two functions answer different questions and are frequently confused, which is worth separating clearly. WHOIS queries a registry and returns administrative information about who holds a domain or an address block and when the registration expires, which is data about ownership and has nothing to do with whether anything works. DNS queries return the records that determine where traffic actually goes, so an A or AAAA record resolves a name to an address, MX directs mail, NS delegates a zone, and TXT carries the verification and policy records that mail authentication depends on. Being able to ask both from one place is useful because a problem that presents as a website being unreachable is frequently a registration that lapsed rather than a server that failed, and those two look identical from a browser. Reverse lookups on an address show which names point at it, which is a quick way to understand whether a host is dedicated or shared.
The output is registry and resolver data presented largely as returned, so interpreting it requires knowing what the fields mean. It reports rather than explains, which is appropriate for the audience and unhelpful to anyone else.