What is an HTTP status code?

Every time a browser asks for a page, the server first returns a three-digit number that sums up the result. The first digit gives the class: 2xx success, 3xx a redirect to another address, 4xx a problem with the request or with access, and 5xx an error on the server side. CheckNet opens the site from several countries and shows each code and time, so you can see whether the site answers the same everywhere.

The common codes

• 200: the page came back fine.
• 301 and 302: the server sends you to another address; 301 is permanent, 302 temporary. Redirects from HTTP to HTTPS, or from the bare domain to www, are usually these.
• 403: the server understood the request but refuses it. Access settings, a web application firewall (WAF) or a country block can all cause it.
• 404: that address was not found on the server.
• 429: too many requests arrived in a short time and the server is rate limiting them; a Retry-After header may say when to try again.
• 451: access is denied because of a legal demand (RFC 7725). The standard asks whoever does the blocking to identify itself with a Link header using rel="blocked-by".
• 500: an internal error in the site’s own application.
• 502: a proxy or CDN got an invalid response from the origin server.
• 503: the server is temporarily unable to answer, for example under heavy load or during maintenance.
• 504: a proxy or CDN got no response from the origin server in time.

Why a site does not open from some countries

If a site returns 200 from most countries but 403 or 451 from one or a few, the site itself probably blocks those places. Some foreign services, citing sanctions law or their own policy, recognise users in Iran by their IP and turn them away. That is different from filtering inside Iran: there the Iranian provider stops the connection; here the foreign site does. For filtering, use the “Is it blocked?” page.

Another reason is bot protection. Many sites sit behind a CDN and a WAF that treat requests from data centres as suspicious. Globalping probes mostly run in data centres, so they may get a 403 or a challenge page while the same site opens fine in your browser.

For site owners: checking each class

1. Enter the full address on CheckNet’s “Does it open everywhere?” page and see whether the code is the same in every country or differs only in some.
2. For 3xx, follow where the redirect goes. A redirect loop (between HTTP and HTTPS, for example) or a redirect to the wrong address is the most common problem.
3. If 403 comes only from some countries, check the country rules, IP reputation and bot protection in your CDN or WAF panel, and find which rule blocked the request.
4. For 404, recheck the address for upper and lower case and the trailing slash, and after moving pages add 301 redirects from the old addresses.
5. For 429, check the rate limit on your server or CDN; it may be too strict for ordinary users too.
6. For 5xx, read the application and server error logs first. For 502 and 504, check that the origin is up and that the CDN can reach it; for 503, check server load and maintenance mode.
7. After each change, check again with CheckNet and compare response times between countries; a much longer time in one region means the server is far from it or the path there has trouble.

Do not treat one error from one probe as final. Check several times and from several countries; a passing network error or bot protection in one data centre is common.