howtofindtheip.com

Reverse IP Lookup

Every IP address can have a name. Enter an IPv4 or IPv6 address to resolve its reverse DNS (PTR) record and see which hostname is registered to it.

What reverse DNS (PTR) is

A normal DNS lookup turns a name into a number: example.com → 93.184.216.34. Reverse DNS does the opposite — given an IP address, it asks DNS for the hostname registered to it, via a special PTR record stored under in-addr.arpa (IPv4) or ip6.arpa (IPv6).

For example, the PTR record for 8.8.8.8 resolves to dns.google. Addresses without an owner-configured PTR — most home connections — return no record at all, which is a perfectly normal result on this tool.

Why PTR records matter

  • Email delivery. Mail servers routinely reject messages from addresses without a valid PTR (or one that doesn't match the sending hostname). If you run a mail server, a correct PTR is mandatory.
  • Log readability. Server logs and traceroute hops become human-readable when addresses resolve to names like gateway.isp.net.
  • Reputation checks. Combined with our blacklist check and proxy check, the PTR helps profile an unknown address.

Reverse DNS vs "reverse IP" domain lookup

Two different things go by the "reverse IP" name:

  • Reverse DNS (this tool) — the canonical hostname of one IP, straight from DNS. Authoritative and exact.
  • Reverse IP domain lookup — a listing of all websites hosted on a shared IP, built from hosting databases rather than DNS. Useful for investigating a suspicious server; every major webmaster tool offers one.

Tip: PTR records are controlled by whoever owns the IP range — usually your ISP or hosting provider. To change yours, contact them, not your domain registrar.

Not sure which address to start with? Find your own IP first — it's pre-filled for you above.

FAQ

Reverse IP questions

What is a reverse IP lookup?

A reverse IP lookup resolves an IP address back to a hostname using its reverse DNS (PTR) record — the opposite of a normal DNS lookup, which turns a hostname into an IP.

Why do mail servers require a PTR record?

Because spam machines rarely bother to configure one. Most mail servers reject or penalise email from addresses without a valid PTR that also matches the sender's hostname (forward-confirmed reverse DNS).

What's the difference between reverse DNS and reverse IP domain lookup?

Reverse DNS (PTR) maps one IP to its canonical hostname. A "reverse IP domain check" lists every website hosted on the same IP — a different technique based on web-hosting databases. This tool performs true reverse DNS.