1. Terminology
    1. Cache miss occurs when no content at the cache location
    2. Cache fill occurs following a cache miss
    3. Cache is filled from the backend or a nearby cache
    4. Cache key is the identifier for cached content
  2. Configuration
    1. Improve Cache Key Hit Ratio by using the entire URL
    2. Instance groups and objects use cache control headers
    3. Whitelist/blacklist query strings to limit caching
    4. Add headers to web server config to allow caching
    5. Cloud Storage objects offer per object controls
    6. Objects must be public (or signed URL) to be cached
    7. CDN does not compress / decompress content, but can serve compressed content from backend
    8. Set expiration for time sensitive metrics