What a Reverse IP Lookup Shows
A normal DNS lookup turns a domain into an IP address. A reverse IP lookup starts from an IP address and lists the domains that point to it. Try it with our Reverse IP Lookup.
Like reverse MX, this cannot be answered by DNS alone, because DNS stores records per domain. The list comes from a database of observed DNS answers. Our database is built from lookups made on this site, so results show domains we have seen, not necessarily every domain on the server.
Reverse IP vs. Reverse DNS
The names sound similar but answer different questions:
- Reverse DNS (PTR): the one hostname that the owner of the IP address has assigned to it, such as
server12.host.example. See Reverse DNS and PTR records. - Reverse IP: all domains whose A records point to the address, collected from observations.
Why One Address Can Host Many Sites
Web servers can host many websites on a single address because browsers send the requested hostname with each request. On shared hosting, hundreds of small sites commonly share one address. On a CDN such as Cloudflare, an address can front an enormous number of unrelated sites, so a reverse IP list for a CDN address says almost nothing about any single site.
Practical Uses
Checking Your Neighbors on Shared Hosting
If your server’s address ends up on a blacklist because of another site, your email and reputation suffer too. A reverse IP lookup shows who you share the address with; check the address itself with the Spam Database Lookup and read how to get delisted.
Migrations
Before retiring a server, list the domains still pointing to it so none are forgotten.
Investigating Related Sites
Scam and phishing sites are often hosted together on small servers. A reverse IP lookup on a suspicious site’s dedicated server can reveal its siblings. Combine it with Reverse NS Lookup and the methods in Reverse WHOIS after GDPR.
How to Interpret the Results
| Result | Likely meaning |
|---|---|
| One or a few domains | Dedicated server or VPS |
| Dozens to hundreds of unrelated domains | Shared hosting |
| Very large or unrelated mix on a CDN network | CDN edge address; not meaningful |
To see which network an address belongs to, check it with IP Location or ASN Lookup.
