TroubleshootingWebsite not loading?
When a website fails, check the layers in order: DNS, network reachability, open ports, HTTP response, browser behavior and server application logs.
Start with the visible symptom
Different failures point to different layers. A browser message about DNS usually means the domain did not resolve. A connection timeout may mean the server IP exists but the port is blocked or the service is down. A redirect error points to HTTP configuration. A blank page with HTTP 200 may be an application or front-end issue.
The fastest path is to avoid guessing. Use each test to eliminate a layer. If DNS is wrong, port checks do not matter yet. If port 443 is closed, HTTP headers cannot be fetched reliably. If headers show a 500 error, the network may be fine while the application is failing.
Checklist
1. DNSCheck A, AAAA and CNAME records.Use DNS Lookup.
2. IP / ASNConfirm the domain points to the expected provider.Compare public IP and ASN.
3. PingTest basic reachability, if ICMP is allowed.Failure is not final proof of outage.
4. Port 443Confirm HTTPS accepts connections.Use Port Check.
5. HeadersInspect status, redirect, cache and security headers.Use HTTP Header Check.
6. BrowserCompare cache, cookies, language and device behavior.Use Browser Information.
Common causes
- DNS record points to an old server.
- AAAA record exists but IPv6 hosting is not configured.
- Firewall or cloud security group blocks port 443.
- HTTPS certificate is expired or missing for the hostname.
- Redirect loops between HTTP, HTTPS, www and root domains.
- CDN cache serves old or broken content.
- Application server returns 500 or 503 behind a working proxy.
- Browser cache, cookies or extensions affect only one device.
If the issue affects everyone, focus on DNS, hosting, firewall, certificate and server logs. If it affects one user or one network, compare IP location, VPN, browser data and local DNS cache.