reverselookups
Reverse lookups refer to the process of retrieving information associated with a value by consulting a directory or index that maps data in the opposite direction of a standard lookup. The term is used in several domains, including networking, telephony, and data directories. In networking, the most common example is reverse DNS, which maps an IP address to a canonical host name. This is achieved through PTR records in the DNS, stored under the reserved in-addr.arpa for IPv4 and ip6.arpa for IPv6. The IP address is reversed in the query, and the corresponding PTR record must exist and be controlled by the owner of the host or network.
Reverse lookups are frequently used in email delivery and anti-spam systems, where mail servers perform a reverse
Limitations include incomplete mappings, dynamic addressing, privacy restrictions, and the possibility of spoofed or misleading results.