NetCheck Tools

Reverse DNS Lookup

Enter an IPv4 or IPv6 address to find the hostname registered for it (its PTR record).

How reverse DNS works

Reverse DNS uses a special DNS tree: IPv4 addresses are looked up under in-addr.arpa and IPv6 addresses under ip6.arpa. The owner of the IP block — typically a hosting company, cloud provider or ISP — controls these zones, which is why you configure PTR records with your server provider rather than at your domain registrar.

Common uses

  • Mail server setup: verify your sending IP's PTR matches your mail hostname before going live
  • Log analysis: turn raw client IPs in access logs into readable hostnames
  • Abuse and security research: identify the network or provider behind a suspicious IP

Once you know the hostname, run a forward DNS lookup on it to confirm it points back to the same IP (forward-confirmed reverse DNS).

Frequently asked questions

›What is a reverse DNS lookup?

A reverse DNS lookup resolves an IP address back to a hostname using PTR records. While a normal (forward) lookup answers “which IP serves example.com?”, a reverse lookup answers “which name is registered for 93.184.216.34?”.

›Why does my IP have no PTR record?

PTR records are published by whoever controls the IP range — usually your hosting provider or ISP, not your domain's DNS provider. Many IPs simply have none configured. If you run a mail server, ask your provider to set the PTR to your mail hostname.

›Does reverse DNS matter for email deliverability?

Yes, a lot. Most receiving mail servers check that the sending IP has a PTR record and that it matches the server's HELO hostname (forward-confirmed reverse DNS). Missing or generic PTR records are a common reason mail lands in spam.

›Can I reverse-lookup an IPv6 address?

Yes. Paste any public IPv6 address (for example 2606:4700:4700::1111) and the tool will query its PTR record the same way as for IPv4.

Related tools

DNS Lookup

Query all standard record types for a domain.

DNS Checker

Verify DNS records after making changes.

Port Checker

Test whether a TCP port is open on a host.