Reverse DNS (PTR) lookup: what hostname does an IP resolve to?
Look up the PTR record for an IPv4 or IPv6 address to see the hostname it reverse-resolves to, if any, since many receiving mail servers check for a matching, sensible PTR record as a basic anti-spam signal before accepting mail.
What the result means
A missing PTR record is normal, especially on residential or dynamic IP ranges — it is set by whoever owns the IP block, not by the person using the address day to day.
Next step
Confirm the forward record matches with a DNS lookup, or check your own IP's details.
How it works and limits
This tool converts the IP address you enter into its reverse-lookup name — in-addr.arpa for IPv4 (RFC 1035) or
ip6.arpa for IPv6 (RFC 3596) — and queries that name’s PTR record through the same DNS-over-HTTPS proxy as the
general DNS lookup tool.
Reading the result
A PTR record maps an IP back to a hostname, the reverse of a normal A/AAAA lookup. It is set by whoever controls the IP block — usually an ISP or hosting provider — not by the person using the address day to day.
Limits
- Not every IP has a PTR record; a missing result is normal for most residential connections.
- A PTR record is not verified against the forward A/AAAA record unless you also look that name up (use the DNS lookup tool) — a mismatch is a known spoofing/misconfiguration signal, not checked automatically here.
- No query is logged; see /legal/privacy/.
Frequently asked questions
Why do mail servers care about reverse DNS?
Many receiving mail servers check that a sending IP has a matching, sensible PTR record as a basic anti-spam signal.
Why does my IP have no PTR record?
Reverse DNS is controlled by whoever owns the IP block (often your ISP or hosting provider), not by you — residential IPs frequently have generic or no PTR records.