Reverse DNS Lookup
Enter an IP address to find the hostname its owner has set in reverse DNS.
About the Reverse DNS Lookup tool
A normal DNS lookup turns a name into an IP. Reverse DNS does the opposite: it asks what hostname an IP address claims for itself. That answer lives in a PTR record, stored under the special in-addr.arpa zone for IPv4 and ip6.arpa for IPv6. This tool queries public resolvers and returns the PTR hostname registered for the address, or tells you that none is set.
How to use it
- Enter an IP address such as
1.1.1.1. - Submit to fetch its PTR record.
- Read the hostname returned, for example
one.one.one.one.
Mail servers rely on reverse DNS heavily: many reject mail from IPs whose PTR is missing or does not match the sending host, so checking it is a key step when fixing email deliverability. Remember that the PTR is set by whoever controls the IP block, so it may be generic or absent, and a matching PTR alone does not prove identity. The IP you enter is sent to our server only to run the query, and is not stored.
Frequently asked questions
What is a PTR record?
A PTR (pointer) record maps an IP address back to a hostname. It is the record a reverse DNS lookup returns, stored in the in-addr.arpa zone for IPv4 and ip6.arpa for IPv6.
Why does my IP have no reverse DNS?
PTR records are optional and controlled by whoever owns the IP block, usually your hosting or internet provider. If none is configured, the lookup returns no result.
Why does reverse DNS matter for sending email?
Many mail servers check that a sending IP has a valid PTR record and that it matches the server's forward DNS. A missing or mismatched PTR is a common reason legitimate mail is rejected or flagged.
Does a matching reverse DNS prove who owns a server?
No. The hostname is whatever the IP owner chose to set, so it is a hint, not proof. Treat it alongside forward DNS and WHOIS data, not as a sole source of trust.