Reverse DNS (PTR) Lookup
Look up the hostname (PTR record) for an IP address.
Reverse DNS (PTR) lookup finds the hostname associated with an IP address. It works in the opposite direction of a forward lookup (domain → IP), letting you identify an IP seen in server logs or check that a mail server's PTR is set up correctly. Both IPv4 and IPv6 are supported. For the opposite direction — a forward domain→IP lookup — use DNS Record Lookup.
The lookup reverses the IP and queries the PTR record under the in-addr.arpa (IPv4) or ip6.arpa (IPv6) domain via a public resolver over DNS over HTTPS. Just enter an IP. Your input is used only for the PTR query and is not stored externally.
What a PTR record is
A PTR (Pointer) record maps an IP address back to a hostname. For example, 8.8.8.8 becomes the query name 8.8.8.8.in-addr.arpa and resolves to a hostname such as dns.google. PTR is managed separately from forward A/AAAA records, so the two may not always match.
Where it is used
- Mail servers: many receiving servers treat a sending IP without a PTR as spam. A PTR is essentially required for reliable delivery.
- Log analysis: infer which organization or ISP an IP in your access logs belongs to.
- Network checks: confirm forward and reverse mappings agree (FCrDNS).
When the result is empty
PTR records must be set by the IP owner (ISP or cloud provider) in the delegated reverse zone. Most home and dynamic IPs have no PTR or only a generic hostname. An empty result does not mean the IP is invalid.