What is reverse DNS?
Looking up a name from an address
Forward DNS resolves a name to an address. Reverse DNS asks for PTR records associated with an address, using the in-addr.arpa tree for IPv4 or ip6.arpa for IPv6.
A missing record is normal
Not every address has a PTR record. A timeout or resolver failure is also different from a successful query that finds no record. A useful lookup tool should distinguish unavailable results from confirmed absence.
Treat names as clues
The operator responsible for reverse DNS chooses the PTR name. It may describe a router, service or customer connection, but it is not proof of ownership or identity. Forward and reverse records do not always match.
Reverse DNS lookup · Look up an IP address · All tools and guides