Explain advanced distributed cache invalidation strategies in enterprise PHP systems.

Distributed cache invalidation ensures consistency between cached data and source-of-truth systems while maintaining high scalability and low latency.

Cache invalidation is one of the hardest problems in distributed systems because cached data exists across multiple layers:

The challenge is balancing:

Core caching patterns:

Application reads cache first. Misses query database. Application populates cache.

Pros:

Cons:

2.…