PTR record

A DNS record (glossary)DNS record One entry in a DNS zone, made of a name, a type, a TTL and data. Full definition of DNS record that maps an IP address (glossary)IP Internet Protocol The internet's basic rules for sending data, using numeric addresses for every connected device. Full definition of IP back to a hostname, the opposite of an A or AAAA record (glossary)AAAA record A DNS record that points a domain name to an IPv6 address. Full definition of AAAA record. For reverse lookups, these records live under the .arpa (glossary).arpa An infrastructure-only top-level domain, best known for holding reverse DNS records. Full definition of .arpa domain and are set by whoever controls the IP address, not by the domain owner. Mail servers often check them to judge senders.