FREE TOOL / NO ACCOUNT / RUNS ON THE PAGE YOU GIVE IT
IP lookup and reverse DNS
Resolve a hostname to every address it has, see what each address points back at, and check whether that name resolves back to the same address.
We resolve the name to every IPv4 and IPv6 address it has, ask each address what name it points back at, then check whether that name resolves back to the same address.
QUESTIONS ABOUT THIS TOOL
- What is reverse DNS, and who actually checks it?
- It is the PTR record that turns an address back into a name. Mail servers check it hardest: a sending IP with no reverse DNS, or one whose name does not resolve back to it, is a strong spam signal and often a flat rejection. Web servers are not judged on it.
- What does forward confirmed mean?
- The address points at a name, and that name points back at the same address. Anybody who controls an IP block can set a PTR record saying anything, so a pointer on its own proves nothing. Only the round trip does, which is why receiving mail servers insist on it.
- Why does my site show several addresses?
- Usually a CDN or a load balancer returning a set of edge addresses, or DNS round robin spreading traffic across servers. Both are normal. What matters is that every address in the set answers, because a resolver may hand any one of them to a visitor.
- Does having no IPv6 address hurt me?
- Not for ranking. Google crawls over IPv4, so a missing AAAA record costs you nothing in search. It costs you reachability on mobile networks that are IPv6 only, where the connection has to go through a translation layer that adds latency.
- Why do the addresses change between checks?
- A CDN answers with the edge nearest whoever asked, and this tool asks from our servers, not from where you are. So the addresses you see here are the ones a resolver in our location gets, which is usually different from what your laptop sees. Neither is wrong.
A TOOL CHECKS ONCE. SEOBUILDER KEEPS WATCH.
We can watch this for you.
Addresses move when you change host, add a CDN, or a load balancer is reconfigured, and the reverse DNS is usually the half nobody updates. We check yours on a schedule and tell you when the answer changes, alongside whether AI answers name you for your category.