Messages, protection & routes
HTTP, TLS & web servers
See how web requests, HTTPS and reverse proxies work, and use read-only checks to isolate 404 and 502 responses.
- concept
HTTP request and response
Read the method, target, headers, optional body, status and returned content in a small HTTP exchange.
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HTTPS and TLS
Understand what HTTPS protects with TLS, how a browser authenticates a service, and which threats remain.
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Reverse proxy
See how a reverse proxy receives public requests and forwards them to one or more upstream applications.
Explore the idea - troubleshooting
HTTP 404 troubleshooting
Diagnose an HTTP 404 from request, deployment, routing and cache evidence, then test a narrow correction without turning genuinely missing routes into success pages.
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HTTP 502 troubleshooting
Investigate a proxy 502 by separating upstream response failures from 404, 503 and 504 without risky restarts.
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HTTP status codes
An HTTP status code is a three-digit field in a server's HTTP response.
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HTTP redirects
An HTTP redirect is a response directing a client to another URI, usually through a `Location` header and a 3xx status.
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TLS certificates and trust chains
A TLS certificate chain lets a client build a candidate trust path from the service's leaf certificate through one or more issuing intermediates to a configured trust anchor.
Explore the idea - troubleshooting
TLS certificate hostname mismatch
A TLS hostname mismatch occurs when the requested reference identity does not match a supported name in the certificate presented by the server.
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A successful secure connection, an HTTP response and a healthy upstream are different observations. Follow the request through each layer before changing configuration.