Free website tool
Reverse IP Lookup (PTR Records)
Find the hostname behind an IP address from its PTR record, and check that it resolves back to the same IP.
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How reverse DNS works
Every public IP address has a spot in a special DNS zone, in-addr.arpa for IPv4 and ip6.arpa for IPv6. The network that owns the address can publish a PTR record there, naming the host. Hosting companies usually set something like server123.examplehost.net; shared hosting rarely names an individual website.
Enter an IP address, or a domain to look up the reverse DNS of every address it points to. For each one you also see the network (ASN) that announces it.
When it matters
- Running your own mail server: receivers expect a forward-confirmed PTR record.
- Reading server logs: a PTR name tells you whose crawler or network an address belongs to.
- Verifying crawlers: Googlebot’s IPs reverse-resolve to googlebot.com or google.com and forward-confirm.
Frequently asked questions
- Can I see all the websites hosted on an IP address?
- Not from DNS alone. DNS only maps names to addresses, and the reverse (PTR) record holds a single name chosen by the address owner. Services that list “all domains on this IP” run passive DNS databases built from huge volumes of observed lookups, and even those are incomplete. We don't have such a database, so this tool shows the PTR record and nothing invented.
- What does “forward-confirmed” mean?
- The PTR name was looked up again and resolves back to the same IP address. This is called forward-confirmed reverse DNS (FCrDNS). Mail servers check it: a sending server without a matching PTR record is much more likely to land in spam or be rejected.
- How do I set a PTR record for my server?
- Reverse DNS is controlled by whoever owns the IP address, not by your domain's DNS host. For a VPS or dedicated server, look for “reverse DNS” or “PTR” in your hosting provider's control panel, or ask their support. Set it to a hostname that has an A record pointing back to the same IP.