What reverse DNS tells you
A standard DNS lookup turns a name into an IP. Reverse DNSdoes the opposite: it asks "what hostname is registered for this IP?" via a PTR record stored under the special in-addr.arpa (IPv4) or ip6.arpa (IPv6) zones.
Where it's used
- Email deliverability: receiving servers check that a sending IP's PTR matches its forward record.
- Network diagnostics: identifying which host or provider an address belongs to.
- Logging: turning raw IPs in logs into readable names.
Related tools
Want your own details? See your public IP, its location, and run a forward DNS lookup.
Frequently asked questions
What is a reverse DNS (PTR) lookup?
A reverse DNS lookup maps an IP address back to a hostname using a PTR record. It's the opposite of a normal lookup, which maps a name to an IP. For example, 8.8.8.8 resolves to dns.google.
Why doesn't my IP have a PTR record?
Not every IP has reverse DNS configured. Home/residential IPs often have a generic ISP-assigned PTR or none at all. Reverse DNS is set by whoever controls the IP block (usually your ISP or host).
Why is reverse DNS important?
Mail servers use it to help verify senders and fight spam. A missing or mismatched PTR can get your email rejected. It's also handy for diagnostics and for working out what owns an IP.
Does it work for IPv6?
Yes. Enter an IPv6 address and we build the ip6.arpa reverse name automatically before querying its PTR record.