How Nginx Caching Boosts Performance: 404‑Driven and Memcached Strategies Explained

Web caching leverages the principle of temporal locality by storing copies of frequently accessed resources on the Nginx server, reducing traffic to backend servers, lowering latency, and improving robustness when backends fail.

NGINX Cache Implementation

1. 404‑Error‑Driven Cache

When a client requests a resource that is not present in the local cache, Nginx returns a 404 error, captures it, forwards the request to the backend, returns the response to the client, and stores the result for future requests.

2. Resource‑Not‑Found‑Driven Cache

This method is similar to the 404‑driven approach but uses an if condition inside a location block to trigger caching without generating a 404 error.

Configuration example:

Both mechanisms cache only responses with a 200 status and cannot cache dynamic query strings such as getsource?id=1 and getsource?id=2, which return the same resource. In practice, Nginx is often combined with a Squid proxy for more flexible caching.

3. Memcached‑Based Cache

Memcached allocates memory to store key/value pairs in a hash table. The server computes the hash of a key to locate the data, and the client queries the appropriate server to retrieve the cached value.

Understanding these caching strategies helps developers optimize web performance and deepen their grasp of server‑side technologies.