🔄 Reverse DNS Lookup

Perform reverse DNS lookups to find the hostname(s) associated with an IP address. Useful for identifying the domain name behind an IP.

Enter IP Address:

💡 Tip: Enter an IP address and click "Reverse Lookup" to find associated hostnames.

Enter an IP address and click "Reverse Lookup" to view results.

How an address is turned back into a name

Reverse DNS is a normal lookup on a rewritten name. The address is reversed and given a special suffix, and the PTR record found there is the hostname:

8.8.8.8  becomes  8.8.8.8.in-addr.arpa  ->  dns.google

IPv6 uses ip6.arpa the same way, one nibble at a time. Your browser does none of this: the address you enter is posted to SimpleMoney's API, the query is run there, and the result you read is the public answer any server on the internet would get for that address.

Who controls the answer

This is the part that surprises people. A PTR record is not published in your own DNS zone — it belongs to whoever owns the address block, which is your ISP or hosting provider. You can point a name at an IP you do not own, but you cannot make that IP point back at you.

No PTR record is normal, not a fault. Plenty of addresses have none.
A generic hostname such as 203-0-113-45.dsl.example.net marks a residential or dynamic address, assigned in bulk by the ISP.
Shared hosting gives one PTR for an address serving hundreds of sites, so the name you get back is usually the host's, not the website's.

Mail servers check this both ways. They take the PTR, then resolve that hostname forward and expect the original address back. A PTR pointing at a name that does not resolve to the same IP is worse than having none.

Frequently asked questions

Why can I not add a PTR record in my DNS panel?

Because reverse DNS is delegated with the address block, not the domain. Ask the provider that assigned the IP to set it; most hosts expose it as a single field on the server or as a support request.

Does a mail server need reverse DNS?

In practice, yes. A sending IP with no PTR, or one whose hostname does not resolve back to it, is widely treated as a spam signal and often rejected outright.

Can one IP address have several hostnames?

Multiple PTR records are legal but a bad idea — checkers only look at the first answer they like, and the result becomes unpredictable. One address, one authoritative name.