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Reverse IP & Reverse DNS Lookup

Find the host name behind an IP address (PTR record) and check that it points back to the same address.

Try an example

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    8.8.8.8 ↔ dns.google

    Forward-confirmed: the PTR name points back to the same address (FCrDNS). Mail receivers look for this.

IP addressPTR host nameForward-confirmed
8.8.8.8 dns.google yes

Other domains on the same IP

Listing every domain hosted on an IP needs a commercial passive-DNS database, which is not connected to this site. DNS itself only stores one PTR name per address.

Who owns 8.8.8.8? →

About this tool

A reverse DNS lookup asks for the PTR record of an address, stored under the special in-addr.arpa (IPv4) or ip6.arpa (IPv6) zones. It turns an IP address back into a host name. Enter a domain and the tool looks up the PTR record of every address the domain points to.

The tool also checks forward-confirmed reverse DNS (FCrDNS): whether the PTR host name resolves back to the same IP. Mail servers use this as a basic trust signal.

Listing all domains hosted on an IP needs a commercial passive-DNS dataset. That part appears only when the site operator has a licensed data provider configured.

How to read the results

  • PTR host name — set by whoever controls the IP block (usually the hosting provider or ISP), not by the domain owner.
  • Forward-confirmed — the host name resolves back to the IP. Required in practice for mail servers.
  • No PTR record — common for web servers and cloud load balancers; a problem only for mail servers.
  • Generic names such as 1-2-3-4.dsl.example.net indicate residential or unconfigured addresses.

Limitations

  • A PTR record shows one chosen name. Shared hosting servers carry many websites, and reverse DNS does not list them.
  • The list of other domains on the same IP requires a licensed data provider (for example ViewDNS.info or SecurityTrails) and is off unless configured.
  • Only public addresses can be looked up.

Frequently asked questions

How do I change the reverse DNS of my server?

Ask the owner of the IP block, usually in your hosting or cloud provider's control panel under "reverse DNS" or "PTR". Your own DNS zone cannot set it.

Why does my mail server need a PTR record?

Many receivers, including large mailbox providers, reject or spam-folder mail from IPs without forward-confirmed reverse DNS.

Can I see all websites on a shared server?

Not from DNS alone. That information comes from passive-DNS databases collected over time, which are commercial products.

What is FCrDNS?

Forward-confirmed reverse DNS: the IP's PTR name resolves back to the same IP. It shows the IP owner and the DNS name owner agree.

What is a PTR record?

The DNS record that maps an IP address to a host name.

Who sets the PTR record?

The owner of the IP block, usually the hosting provider.