DNS (Domain Name System) is a hierarchical and decentralized naming system for Internet connected resources.
DNS maintains a list of domain names along with the resources, such as IP addresses, that are associated with them.
The most prominent function of DNS is the translation of human-friendly domain names to a numeric IP address. This process of mapping a domain name to the appropriate IP address is known as a DNS lookup. dns-lookup
A reverse DNS lookup (rDNS) is used to determine the domain name associated with an IP address.