Reverse DNS: how to look up PTR records and read results

Reverse DNS looks up names associated with an IP address. IPv4 uses names below in-addr.arpa and IPv6 uses ip6.arpa.

In NetKarte

NetKarte converts a public address to a PTR query and displays every returned name. Private, loopback, link-local, and other non-global addresses are not sent externally.

Limitations

The address-side administrator controls PTR records. NetKarte displays returned names but does not automatically check whether their forward lookups return the original IP.

Run a reverse lookup

1. In Reverse DNS, enter a public IPv4/IPv6 address, not a URL or domain.
2. Complete verification and check the normalized target IP.
3. Read each PTR record; several values are not automatically wrong.
4. Use IP information lookup for the registered organization.

Reverse DNS is not a list of every website hosted at an IP. Shared hosting does not require all sites to appear in PTR.

When PTR is absent

No PTR and retrieval failure differ. Skipping a non-public address also says nothing about internal PTR records. Ask the address provider about changes. Adding A to your domain does not automatically create reverse DNS for the IP.