Cacheinnstillinger

Cacheinnstillinger, or cache settings, refer to configuration options that determine how, when, and for how long content is stored in caches and served to users. They apply across several layers of a computing stack, including browser caches, server-side caches, reverse proxies, and content delivery networks (CDNs). The goal is to improve performance and reduce load on origin systems while preserving content correctness.

Key concepts include freshness and validity. Cached resources are assigned a time-to-live (TTL) or a validator such as an ETag or Last-Modified timestamp. Cache-Control headers define how caches may treat a response, with directives like max-age, no-store, no-cache, public, and private. Expires provides an expiry date. When content is stale, caches may revalidate with the origin; some configurations allow serving stale content while revalidation occurs (stale-while-revalidate).

Best practices involve balancing performance and freshness. Static assets with infrequent changes often receive longer TTLs and explicit versioning (fingerprints). Dynamic content may use shorter TTLs, cache-busting query strings, or bypass rules. Use validators and Vary headers to ensure correctness across versions and user contexts. Regular purging and invalidation as content changes is essential for CDN and proxy caches.

Configuration considerations depend on the platform. Browsers rely on HTTP headers, while server caches (for example, Nginx, Varnish) and CDNs provide separate controls for edge caching, origin fetch rules, and purge APIs. Clear documentation and testing help maintain predictable cache behavior.