How to check if a website is blocked

Tell a blocked site from a down site or a bad connection with simple tests: another network, DNS comparison, HTTPS. How to read each result.

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Searching "is this website blocked" usually leads to one of those online checker pages. They can be useful, but they answer a different question than the one you have. This article shows how to check from your side, on your network, and how to read the outcome without jumping to conclusions.

Blocked, down, or broken? Tell them apart

The same error message can come from very different situations. Check these first, because they are quick:

  • Is the site down for everyone? A public "down for everyone or just me" checker tests from its own servers. If it says the site is down, that is your answer and nothing is blocked. If it says the site is up, the problem is between you and the site. Be careful, because a checker's servers sit on a different network than yours and will not see your ISP's filters.
  • Is your connection working at all? Open two or three unrelated sites. If many fail, the problem is your connection, not a block.
  • Is your clock right? A wrong date or time on the phone makes HTTPS certificates look invalid and many sites fail with a certificate error.
  • Is the address correct? A typo or an old bookmark often explains a "not found" error.

Five tests that actually reveal blocking

1. Try another network

Switch from Wi-Fi to mobile data, or borrow a friend's hotspot. If the site opens on one network and fails on the other, the failing network is doing something. This is the single most informative test and costs nothing. The causes are explored in Why does a site open on mobile data but not on Wi-Fi?

2. Read the error carefully

What you seeTypical meaning
"Server not found" or "can't resolve host"DNS failed. Possibly DNS blocking, or just a bad resolver
A page from your ISP, school or router saying access is restrictedAn explicit block page, usually via DNS or an HTTP redirect
"Connection reset" or an immediate failure on HTTPS onlyOften SNI/DPI filtering
Long wait, then "timed out"Packets dropped. May be an IP block, a firewall, or a down server
Certificate warning for a different nameSomething is answering in place of the site. Do not click through

Never accept a certificate warning to "get past" a blocked page. A warning means the connection is not talking to the real site.

3. Compare DNS answers

Ask your network's resolver and an independent resolver for the same name and compare. On a computer you can do this with nslookup example.com and then nslookup example.com 1.1.1.1. If the answers differ and only the independent one works, the network's DNS is lying or failing. A full walkthrough, including dig and curl, is in Which websites are blocked on my Wi-Fi? Different addresses alone are not proof, because large sites return different servers to different networks.

4. Test HTTPS to the real address

If DNS looks fine but the page still fails, the next question is whether the HTTPS handshake is being interfered with. A connection that reaches the server but is reset during the handshake points to name-based filtering. A connection that never reaches the server at all points to an IP or firewall block. This is the logic behind SNI filtering and how splitting beats it.

5. Run Inspect URL

Doing steps 3 and 4 by hand is possible but fiddly on a phone. GreenTunnel's Inspect URL does them for you. Open the tab, type the domain and tap Inspect. It compares your ISP's DNS with encrypted DNS, tries a direct connection to the real IP on port 443, tests HTTPS without any bypass, and then tests it with each bypass technique. The summary card states the verdict in one line: opens without help, fake DNS, name filtered, blocked by IP address, or could not determine. Full explanation: Is a site blocked on your network?

The check runs on your device and goes straight to the site and to the DNS server you chose. We do not collect the domains you inspect.

What each verdict means for you

  • Opens without help: not blocked on this network. If the page still misbehaves, suspect the site, your app, or your device.
  • Fake DNS: turning on encrypted DNS solves it. See DoH and DoT.
  • Name filtered: a bypass technique may work. Use the one Inspect URL found and see How to unblock a website for the full routine.
  • Blocked by IP address: local techniques cannot help. You would need a server of your own or a remote VPN, which are a different kind of tool.
  • Could not determine: try again on another network and see the troubleshooting guide.

Honest limits

A test shows what happens right now on one network. Filters can be rolled out or removed without notice, and an ISP can treat different customers differently. A result today is not a promise for next week. GreenTunnel does not hide your IP address, is not an anonymity tool, and does not promise to open any specific site or to get around any country's firewall.

GreenTunnel is free on Android and iPhone, with optional Premium. See how it works on the home page.

FAQ

Are online "is this site blocked" checkers reliable?

They are reliable for "is it down for everyone". They are not reliable for "is it blocked on my network", because they test from their own servers and cannot see the filters on your ISP, school or router.

Can I check without installing anything?

Yes. Trying another network and running nslookup or dig against two resolvers on a computer needs no extra software. A phone app is simply easier when you are away from a computer.

If the site opens on mobile data, is it definitely blocked on my Wi-Fi?

Not definitely. It could also be a router fault, a DNS cache problem or an IPv6 issue. But it does mean the cause is on the Wi-Fi side of things, which narrows the search a lot.

Does checking a site tell the site or my ISP that I looked?

Checking makes the same kind of connection as opening the site. Your ISP can see the same things as when you browse normally, such as DNS queries unless encrypted and the connection's destination.

Sources

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