Explain Edge Caching vs Origin Caching.
Edge caching stores content on servers near the user for low-latency delivery, while origin caching keeps data on the application’s main server to reduce backend load.
When to Use
Use edge caching (via CDNs) when serving static assets, APIs, or media to a global audience.
Use origin caching for dynamic queries, database lookups, or internal apps where proximity to the user matters less.
Example
A news site caches headlines on edge servers worldwide for fast page loads, while its backend caches recent DB queries at the origin.
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Why Is It Important
Choosing the right caching layer improves scalability, latency, and cost efficiency, directly affecting user experience and backend reliability.
Interview Tips
Define both clearly.
Highlight that edge caching lowers latency for global users, while origin caching accelerates backend performance.
Interviewers expect clarity on trade-offs.
Trade-offs
Edge caching improves performance but adds cache invalidation complexity. Origin caching simplifies control but doesn’t help users far from the data center.
Pitfalls
Common mistakes include relying only on origin caching (hurts global latency), or failing to manage stale data at the edge. Always pair caching with strong invalidation policies.
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