What Is a Reverse DNS Lookup?

In computer networks, reverse DNS lookup or reverse DNS resolution (rDNS) is a query of the Domain Name System (DNS) to determine the IP address of the domain name in questionusually a "forward" reverse DNS lookup for the IP address of a domain name.

The reverse process resolves IP addresses using PTR records. The Internet's reverse DNS database is rooted in the arpa top-level domain.

Although the information [rfc: 1912 RFC1912] (Section 2.1) suggests that "every Internet accessible host should have a name" and "for each IP address, there should be a matching PTR record", which is not an Internet standard It is required that not all IP addresses have a reverse record.

The modern "reverse DNS lookup" should not be confused. The "reverse lookup" (IQUERY) mechanism is written in RFC 1035:

Inverse queries take the form of a single

Domain Name System (

Internet Protocol Address (English: Internet Protocol Address, also translated as Internet Protocol address ), abbreviated as IP Address (English: IP Address), is a digital label assigned to devices using Internet Protocol (English: Internet Protocol) on the network . Common IP addresses are divided into two categories, IPv4 and IPv6, but there are other subcategories that are not commonly used. ^[2]