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Akamai Web Performance study materials
Akamai Web Performance study resources

Akamai Web Performance: Caching and Content Delivery Optimization

Akamai Web Performance · Work through your exam, one topic at a time.

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Caching and Content Delivery Optimization

Cache mechanics

Edge caching decisions depend on cacheability (method, status code, response headers) and freshness (TTL from Cache-Control/Expires, or heuristic/default TTLs). Key headers: Cache-Control (max-age, s-maxage, no-cache, no-store, private, public), Expires, ETag/Last-Modified, Vary, and Age. Understand TTL override at the edge, cache keys (hostname, path, query string, selected headers/cookies), and purge/invalidation (single object, CP code, or tag-based). Tiered distribution adds a parent layer to raise hit ratio and shield origin.

Traps

  • no-cache means revalidate before use, not do not store; no-store is the do-not-store directive.
  • private prevents shared-cache storage, so an edge cannot cache it even with a long TTL.
  • Query strings and cookies in the cache key fragment the cache - high cardinality destroys hit ratio.
  • A long browser TTL on a fingerprinted asset is good; on HTML it delays updates.
  • Purge is not instant everywhere and does not fix a bad cache key.

Rule of thumb

Aim for long TTLs plus content hashing for static assets (effectively immutable), short or revalidated TTLs for HTML, and a minimal cache key. Every field you add to the key can multiply stored variants.

Worked example

A CSS file served with Cache-Control: max-age=31536000, immutable and a hashed filename can be cached for a year at edge and browser. A new release publishes a new hash, so no purge is needed. HTML stays max-age=60 with revalidation.