Reverse DNS and IP address information

What the IP lookup shows

Reverse DNS (PTR)

The name the address points back to. Essential for servers that send mail.

Forward confirmation

Whether the name in the reverse record points to the same address again. Mail servers accept only a reverse record that does.

Announcing network

Which autonomous system (AS number) announces the address to the internet, and which prefix it is part of.

Registration

Which network the regional registry (RIPE, ARIN and so on) lists the address in, who holds it, and where abuse can be reported.

Kind of address

Whether it is a private or reserved address, or part of Cloudflare's network.

Frequently asked questions

What is reverse DNS?

Ordinary DNS turns a name into an address; reverse DNS turns an address into a name. The PTR record is set by whoever provides the IP address, usually the hosting company or internet provider, not by the owner of the domain.

Why does reverse DNS matter for mail?

Receiving servers look at the reverse record of the sending server's address, and at whether that name points back to the address. If either is missing, many of them reject the mail or treat it as spam.

How do I set reverse DNS?

With the provider you got the IP address from: for a VPS or dedicated server, in the client portal or through support. On shared hosting the reverse record of the provider's mail server is what counts, and there is nothing for you to do.

Does the tool show where the server physically is?

No. The country you see is from the registration of the address, not the actual location of the machine; the two often differ.