First of all, what does it mean than an IP resolves to a hostname? You can do a reverse DNS lookup, which uses PTR records. See: https://tools.ietf.org/html/r

First of all, what does it mean than an IP resolves to a hostname? You can do a reverse DNS lookup, which uses PTR records. See: https://tools.ietf.org/html/rfc1033 https://tools.ietf.org/html/rfc1033