Reverse DNS Lookup

Find the name an IP address points back to, and check that the name points to the same address again. Mail servers check exactly this.

  • Free
  • No Sign-Up
  • Live Lookup

Examples:

How to Use

How to use the Reverse DNS Lookup

  1. 01

    Enter an IP

    IPv4 or IPv6.

  2. 02

    Look up

    You get the PTR name and the reverse zone it lives in.

  3. 03

    Check the match

    Forward-confirmed means the PTR name resolves back to the same address.

DNS

About the Reverse DNS Lookup

What reverse DNS is

Normal DNS turns a name into an address. Reverse DNS goes the other way, using a PTR record in a special zone: for 203.0.113.25 the record lives at 25.113.0.203.in-addr.arpa. IPv6 uses ip6.arpa with one label per hex digit.

The PTR record is controlled by whoever owns the IP block (your hosting provider or ISP), not by the owner of the domain. To change it you set it in your provider's panel or ask them.

Why it matters for email

Gmail, Outlook and most mail servers check that a sending server has a PTR record, and many require it to be forward-confirmed: the PTR name must have an A or AAAA record that points back to the same IP. Missing or generic reverse DNS (like 203-0-113-25.dynamic.example.net) is one of the most common reasons new mail servers land in spam.

A good PTR for a mail server is the same name it uses in its SMTP greeting, such as mail.example.com.

For hosting providers

Letting customers set their own PTR (from the VM panel, or through a ticket) prevents a lot of mail delivery tickets. Setting it should come with a check that the forward record matches, or you will end up with names that never confirm.

Reverse DNS Guides

For Mail ServersIPv6 Reverse DNSFCrDNS Check

What it can't tell you

  • An address can have no PTR at all; that is common for VMs that have never been set up for mail.
  • Several PTR records on one address are allowed but confuse mail checks; keep one.

Frequently asked questions

Who controls my reverse DNS?
The owner of the IP block: your hosting provider, data centre or ISP. Set it in their control panel or ask their support; your domain's DNS provider cannot change it.
What is FCrDNS?
Forward-confirmed reverse DNS. The IP's PTR points to a name, and that name's A or AAAA record points back to the same IP. Mail servers use it as a basic sign that a sender is configured on purpose.
Do I need reverse DNS for a web server?
Not for serving websites. It matters for sending email, and some services use it in logs or access checks.
Why does my IP's PTR show my provider's name?
That is the provider's default. It works, but for a mail server you should change it to your own host name.

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