What Is Reverse DNS?

Reverse DNS resolves an IP address to a hostname. It is the opposite of a normal DNS lookup, which resolves a name to an IP.

PTR records

Reverse DNS depends on PTR records stored in special reverse-lookup zones such as in-addr.arpa for IPv4.

Common uses

• Mail server verification
• Logging and troubleshooting
• Basic identity hints for network operators

Important limitation

Reverse DNS is not always configured. Absence of a PTR record does not mean an IP is invalid or malicious.