Infrastructure

The 5xx class indicates the server failed to fulfil an apparently valid request. These drive SLOs and on-call paging. Table of 5xx Codes (selected) Code Name Summary 500 Internal Server Error Generic server failure. 501 Not Implemented Method not supported at server. 502 Bad Gateway Upstream error at proxy/gateway. 503 Service Unavailable Overloaded or maintenance. 504 Gateway Timeout Upstream timeout. 507 Insufficient Storage WebDAV storage failure. 508 Loop Detected WebDAV loop. 510 Not Extended Further extensions required. 511 Network Authentication Required Captive portal/auth needed. 500 Internal Server Error Catch-all for unhandled exceptions. Log with correlation IDs; prefer specific 5xx when possible. ...

Redirects inform clients that a resource has moved. The choice of status code affects method handling, cache persistence, and search engine behaviour. Redirect Decision Flow flowchart TD A[Is the move permanent?] -->|Yes| B[Must the HTTP method be preserved?] A -->|No| C[Must the HTTP method be preserved?] B -->|Yes| D[308 Permanent Redirect] B -->|No| E[301 Moved Permanently] C -->|Yes| F[307 Temporary Redirect] C -->|No| G[302 Found] %% Contextual hints D:::perm --> H[Set long TTL; expect SEO consolidation] E:::perm --> H F:::temp --> I[Short TTL; use for maintenance] G:::temp --> I classDef perm fill:#ddd,stroke:#333,color:#000; classDef temp fill:#eee,stroke:#333,color:#000; Overview Table Code Meaning Method Preserved Cacheable by Default SEO Signal 301 Permanent redirect Not guaranteed Yes Passes link equity 302 Temporary redirect (legacy) Not guaranteed No Limited 307 Temporary, method preserved Yes No Limited 308 Permanent, method preserved Yes Yes Passes link equity 301 Moved Permanently Permanent relocation. Clients may update bookmarks. Caching: Long-lived; set deliberate TTL. ...