How does Cloud CDN handle cache hits and cache misses?

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Cloud CDN (Content Delivery Network) is a service provided by Google Cloud Platform (GCP) that helps deliver content to users with low latency and high availability. It works by caching content in edge locations around the world, closer to the end users, reducing the distance and network hops required to access the content. When a user requests content, Cloud CDN determines whether the requested content is available in its cache or not. This process is known as cache hits and cache misses.

Cache Hits:
When a user requests content that is already cached in an edge location, Cloud CDN responds with the cached content directly from the edge location. This results in faster response times and lower network latency. Cache hits occur when the requested content is present in the cache and is still considered fresh based on the cache expiration settings. Cloud CDN uses various mechanisms to determine the freshness of the content, such as the Cache-Control headers set by the origin server.

For example, let's say a user in New York requests an image file that is already cached in an edge location in New York. Cloud CDN identifies that the requested content is available in the cache and serves it directly from the New York edge location. The user receives the content quickly without the need to fetch it from the origin server.

Cache Misses:
When a user requests content that is not present in the cache or is considered stale, a cache miss occurs. In this case, Cloud CDN fetches the requested content from the origin server and delivers it to the user. Cloud CDN also caches the fetched content in the edge location for future requests, optimizing subsequent responses.

For example, suppose a user in London requests a webpage that is not present in the cache of the London edge location. Cloud CDN identifies the cache miss and fetches the webpage from the origin server. It then delivers the webpage to the user in London and caches it in the London edge location. If another user in London requests the same webpage, Cloud CDN can respond with the cached version, resulting in faster response times.

Cloud CDN also provides options to control cache behavior. Cache control headers, such as Cache-Control and Expires, can be set at the origin server to specify how long the content should be considered fresh in the cache. Additionally, Cache Keys can be configured to control how content is cached and served based on specific URL patterns or query parameters.

Cloud CDN handles cache hits by serving the requested content directly from the cache in the edge location, resulting in faster response times. Cache misses are handled by fetching the content from the origin server and caching it in the edge location for future requests. By leveraging caching and edge locations, Cloud CDN optimizes content delivery for improved performance and user experience.

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