Reverse DNS Lookup
Find the hostname behind any IP address. Reverse DNS (rDNS) uses PTR records to map an IP to a domain or hostname — useful for email checks, server verification, and tracking down who owns an IP.
Look Up Reverse DNS
Enter an IP address to see its hostname (PTR record).
What Is Reverse DNS Lookup?
Normal DNS lookup answers: “What IP address does this domain point to?” Reverse DNS asks the opposite: “What hostname or domain is assigned to this IP address?” It uses a separate part of the DNS system called the in-addr.arpa (IPv4) or ip6.arpa (IPv6) zones, where PTR (pointer) records store the hostname for an IP.
Not every IP has a PTR record. Many home and mobile connections do not. Servers — especially mail servers — often do, because some receiving mail systems check reverse DNS to reduce spam. If you run a server, your host might let you set the PTR record so it matches your hostname.
How to Use Reverse DNS Lookup
Enter any public IPv4 or IPv6 address in the box above and click “Look Up.” The tool queries the same data used by our IP lookup and shows the reverse DNS (hostname) for that IP, plus basic network details. You can test your own server’s IP, a mail server you’re troubleshooting, or any IP you see in logs. For full details (location, ISP, VPN flag), use our main IP address lookup or What is my IP.
Features
- Instant reverse DNS (PTR) result for any public IP
- Works with IPv4 and IPv6
- No signup or API key
- Useful for email deliverability and server checks
Why Use This Tool
Admins use reverse DNS to confirm a server’s hostname matches what it should be (e.g. mail.example.com). Email admins check that sending IPs have valid PTR records to avoid being flagged as spam. Security teams use it to see which hostnames are tied to suspicious IPs. If you’re debugging connectivity, pairing reverse DNS with a ping test or traceroute tool helps identify hops. For forward DNS (domain → IP, MX, etc.), use our DNS lookup.
FAQs
What is reverse DNS lookup?
Reverse DNS (rDNS) looks up the hostname assigned to an IP address. Normal DNS turns a name into an IP; reverse DNS does the opposite using PTR records.
Why would an IP have no reverse DNS?
Many ISPs and hosting providers do not set PTR records. It is optional. Missing rDNS can affect email deliverability since some servers check it.
How do I set up reverse DNS for my server?
PTR records are set by the party that owns the IP block (usually your ISP or host). Contact them to add a PTR record pointing to your hostname.
Is reverse DNS the same as DNS lookup?
No. DNS lookup (forward) resolves a domain to IPs and other records. Reverse DNS resolves an IP to a hostname. Our IP lookup tool shows both.
Is this reverse DNS lookup free?
Yes. The tool is free with no signup. You can look up any public IP.