Reverse DNS
Find the hostname associated with an IP address via PTR record lookup.
Reverse DNS (rDNS) looks up the hostname registered for an IP address by querying its PTR record in the in-addr.arpa (IPv4) or ip6.arpa (IPv6) zone. Enter an IPv4 or IPv6 address to see the name its owner has published. It's widely used to verify mail servers, read traceroute output, and confirm an IP's forward and reverse records match.
Frequently asked questions
What is a PTR record?
A PTR (pointer) record maps an IP address back to a hostname — the reverse of an A or AAAA record. It lives in a special reverse-DNS zone managed by whoever controls the IP block.
Why does an IP have no reverse DNS?
Reverse DNS is optional and controlled by the IP’s owner (usually the hosting provider or ISP), not the domain owner. Many addresses simply have no PTR record published.
Why doesn’t reverse DNS match the website’s domain?
Forward and reverse records are set by different parties. A server at example.com often returns a provider hostname on reverse lookup, which is perfectly normal.
Why does reverse DNS matter for email?
Many mail servers reject or downgrade mail from IPs whose PTR record is missing or doesn’t align with the sending domain, so correct rDNS improves deliverability.
Can one IP return multiple hostnames?
Yes. An address can have several PTR records, though a single, consistent record is best practice for mail and diagnostics.