Optimizing Caching

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Useful Links:
- Configuring caching
Exam Tips:
- Cache Hit = Matching object, delivered from cache.
- Cache Miss = Matching object not cached.
- Maximize the cache hit ratio.
- ACM has to be provisioned in US-East-1 for global services like CloudFront.
- Forward what the application needs.
- Cache based on what can change the objects.S
- The more things are involved in caching the less efficient.
- Cannot use self signed certificates.
- Can change caching behavior based on:
  - cookies
  - selected request headers
  - query strings
- Know the TTL values:
  - Default TTL = 24 hours
  - Can set minimum and maximum
- Origin Headers:
  - Cache-Control max-age (seconds)
  - Cache-Control s-maxage (seconds)
  - Expires (Date & Time)
- Cache invalidations:
  - Performed on a distribution
  - Applies to all edge locations - takes time
- More frequent cache HITS = lower origin load
- 304 Not Modified
- 200 Ok
- Versioned File names:
  - Logging
  - Caching
  - Consistency
  - Price