Reverse DNS Lookup: PTR Record for an IP Address

Find the PTR host name for an IP and check it points back.

Use via API

PTR (reverse DNS) names for a public IPv4 or IPv6 address, with a forward-confirmed (FCrDNS) check. Send JSON, get JSON back; this one reaches the network from PithLab’s server.

POST https://pithlab.com/api/v1/tools/reverse-dns-lookup

curl https://pithlab.com/api/v1/tools/reverse-dns-lookup \
  -H "Authorization: Bearer $PITHLAB_KEY" \
  -H "Content-Type: application/json" \
  -d '{"ip":"8.8.8.8"}'

Fields and response OpenAPI document Get an API key

About the Reverse DNS Lookup

Find the host name behind an IPv4 or IPv6 address from its PTR record, and check that the name points back to the same address (forward-confirmed reverse DNS).

How to use the Reverse DNS Lookup

Enter a public IPv4 or IPv6 address, such as 8.8.8.8 or 2606:4700:4700::1111.
Press Look up. PithLab's server asks public DNS resolvers for the address's PTR record.
Each name found is looked up again to confirm it points back to the same address, which mail servers check before trusting a sender.

Examples

Google Public DNS

Input

8.8.8.8

Output

Forward-confirmed: 8.8.8.8 → dns.google → 8.8.8.8.

Frequently asked questions

What is forward-confirmed reverse DNS?

The IP's PTR record gives a name, and that name's A or AAAA record lists the same IP. Many mail servers reject or penalise email from servers that fail this check, because spammers rarely set it up.

How do I set a PTR record for my server?

PTR records belong to whoever owns the IP block, usually your hosting provider or ISP, not your domain's DNS. Look for a reverse DNS or rDNS setting in your hosting control panel, or ask their support.

Can I look up private addresses like 192.168.1.1?

No. Only public addresses are checked, through public resolvers, so names used inside private networks aren't visible.