Find the Hostname Behind an IP
Reverse IP & PTR Lookup

A reverse IP lookup (also called reverse DNS or rDNS) maps an IP address back to a hostname. It queries the PTR record in DNS for the reversed IP under the in-addr.arpa domain. For example, to look up 1.2.3.4, it queries 4.3.2.1.in-addr.arpa for PTR records.

A PTR (Pointer) record is a DNS record that maps an IP address to a hostname. It's the opposite of an A record. PTR records are commonly used for email server verification — many mail servers check that the sending IP has a valid PTR record matching the server's hostname.

Not all IP addresses have PTR records configured. The IP's owner (usually the ISP or hosting provider) must explicitly set up the reverse DNS entry. Residential IPs often have generic PTR records set by the ISP, while some IPs may have no PTR record at all.

Email servers often perform reverse DNS lookups on the sending server's IP to verify its identity. If the PTR record doesn't match the HELO/EHLO hostname or is missing entirely, the receiving server may flag the email as spam or reject it outright.

Yes! If you enter a domain name, the tool will first resolve it to an IP address using a DNS A record lookup, then perform the reverse lookup on the resolved IP.