Reverse DNS Lookup

Find the hostname an IP address points back to, check whether it is forward-confirmed, and see which domains resolve to the address.

Try: 8.8.8.8 · 1.1.1.1 · 2001:4860:4860::8888 · AS15169

How reverse DNS works

Normal DNS turns a name into an address. Reverse DNS does the opposite: the owner of an address block publishes PTR records under the special in-addr.arpa (IPv4) or ip6.arpa (IPv6) zones. For example, the PTR record for 8.8.8.8 lives at 8.8.8.8.in-addr.arpa and returns dns.google.

Because only the network owner controls the PTR record, the hostname is a strong hint about who runs the address — names like server-203-0-113-5.cloud.example.com or pool-198-51-100-7.dynamic.example-isp.net reveal cloud hosting or a residential pool.

Forward-confirmed reverse DNS (FCrDNS)

Anyone who controls an address block can set any PTR name, including one that impersonates another domain. Forward-confirmed reverse DNS closes that gap: the hostname from the PTR record is resolved forward again, and the result must include the original address. Mail servers use FCrDNS to reject spoofed senders, and search engines use it to verify their crawlers. IPDebrief profiles show whether each address is forward-confirmed.

Reverse DNS vs. hosted domains

A PTR record names one host, but many websites can share one address. The hosted domains list on each profile shows names observed resolving to the address or appearing on its TLS certificates, which is usually far more informative for shared hosting and CDNs.

Command-line reverse DNS

You can query PTR records yourself. On Linux or macOS, dig -x 8.8.8.8 +short or host 8.8.8.8 returns the hostname; on Windows, use nslookup 8.8.8.8 or Resolve-DnsName 8.8.8.8 -Type PTR in PowerShell. To check forward confirmation, resolve the returned hostname again with dig dns.google +short and confirm the original address appears in the answer.

Command-line results reflect a single resolver at a single moment. IPDebrief profiles record PTR answers over time, confirm them forward, and place them next to ownership and reputation data so you can judge whether a hostname is plausible for the network that announces the address.

Frequently asked questions

Why does an IP have no reverse DNS?

PTR records are optional. Many residential, mobile and cloud addresses have none or a generic one, and some networks delegate reverse zones to customers who never configure them.

Can an IP have more than one PTR record?

It is technically allowed but discouraged; most software uses only the first answer. Profiles list every PTR name returned.

Does reverse DNS matter for email?

Yes. Most receiving mail servers expect the sending IP to have a PTR record whose hostname resolves back to the same IP. Missing or mismatched reverse DNS is a common reason mail lands in spam.

How do I change reverse DNS for my IP?

Ask whoever allocated the address — your hosting provider, cloud console or ISP. Only the holder of the reverse zone can change PTR records.