DNS
A public resolver (Google, or Cloudflare if Google does not answer) is asked for the A and AAAA records. NXDOMAIN means the name is not in DNS. An address means the name exists, even if the website behind it is broken.
Is the website up?
Type an address. The page asks public DNS where the name points, then asks your browser whether it can get a response from where you are sitting.
How to read the result
Your browser
The page then requests the URL from this browser. If a response comes back, the host answered your network. Browsers will not reveal the HTTP status code to another website, so this cannot tell a clean 200 from a 500.
What to do with each outcome
- Responding here. DNS has an address and your browser got a reply. If the page still looks wrong, the problem is inside the site, not a total outage. Try a reload, then another device on the same network.
- DNS works, browser does not. The domain exists. Your path to it does not. Switch between Wi-Fi and mobile data. If it fails on both, the site or its TLS certificate is a stronger suspect.
- Not resolving. Check the spelling. A name that is not in public DNS will fail for other people too, unless they use a private network where that name exists.
- Lookup failed. The check itself could not reach a DNS resolver. That says something about this browser's network, not about the website you typed.
This is not a monitor. It does not probe the site every minute, from many countries, or by email. One check answers “what happens from here, right now?” Apps such as Instagram or a bank's mobile app can fail while their marketing website still answers, and the other way around. Paste the address you actually cannot open.
Common questions
Is a green result proof the site is up for everyone?
No. It proves your browser got a response and public DNS had a record. Another country, or a mobile network, can still fail.
Why not just ping it?
A web page cannot send an ICMP ping. It can make an HTTP request and a DNS-over-HTTPS query. Those are the two signals on this page.
Do you store the sites I look up?
No history is kept by this site. The hostname does go to Google or Cloudflare for the DNS query, and your browser contacts the site itself. See the privacy notice.