Reverse DNS
Resolve PTR / hostname from an IP.
Enter a target
e.g. 8.8.8.8 — press ⏎ / ⌘⏎
What is Reverse DNS?
Reverse DNS resolves an IP address back to a hostname. For IPv4 the query is the reversed address plus .in-addr.arpa; the PTR record lives in that special zone.
PTR is critical for mail delivery: Gmail, Outlook and most corporate filters reject or flag mail from IPs with no reverse DNS, or whose reverse name doesn't confirm forward.
PTR is published by the owner of the IP block — your hosting provider, or you via an RIR — not by the domain owner, so adding one usually means going through your provider's panel or support.
Frequently Asked Questions
8 questionsWhat is a PTR record?
PTR is the reverse-DNS record mapping an IP back to a hostname. For 1.2.3.4 the query goes to 4.3.2.1.in-addr.arpa and returns the name.
Why does my IP have no PTR?
PTR records are managed by the owner of the IP block — usually your ISP or cloud provider. You must request one from them; residential IPs often have generic or empty PTRs.
Why does PTR matter for email?
Most mail servers expect the connecting IP to have a PTR that matches forward DNS (FCrDNS). Without it your mail may be marked as spam or rejected outright.
Can one IP have multiple PTR records?
Technically yes, but it's discouraged — many systems read only the first. A single accurate PTR per IP is the safest setup for mail servers.
How do I add a PTR record?
Not through your domain's DNS panel — through whoever owns the IP. Hosting and cloud providers expose a "reverse DNS" or "PTR" field; otherwise you file a support request. If you hold your own IP block, your RIR delegates the reverse zone to you.
Can an IP have more than one PTR?
Technically yes, but it's discouraged. With multiple PTRs it's undefined which one a receiver picks, and some spam filters penalise it. Publish exactly one per IP.
Does reverse DNS work differently for IPv6?
Same idea, different zone: IPv6 lives under ip6.arpa with every hex digit reversed and dot-separated. That makes IPv6 PTR names very long and error-prone to type by hand.
What does forward-confirmed reverse DNS mean?
Querying A/AAAA for the name the PTR gives returns the IP you started from. Large mail providers expect this — a PTR merely existing is not enough.