In most of the connections made through the Internet the name of the machines is used instead of their IP addresses. For obvious reasons names are easier to memorize than numbers. However, Internet connections between computers connected to this network will be performed using IP addresses. Therefore, before starting the connection, a translation of the name of the machine to its IP address is made. This process is called direct DNS resolution, that is, name-to-IP-address translation.
Often it is necessary to also do the reverse operation, from which the name Reverse Resolution arises.
In this conversion, from the IP address of a device, it tries to reach the name associated with it.
For the reverse resolution process to be possible, it is necessary to use the "in.addr-arpa" domain, a historical abbreviation for Arpanet Inverse Address.
The DNS delegation of this domain is the responsibility of the Internet Registries, since they are responsible for the assignments of IP addresses.