CDN strategy: the invisible infrastructure decision
It's easy to set up once and never think about again — which is exactly the risk.
A CDN gets configured once during initial setup and then rarely revisited, which is unfortunate, because caching strategy has an outsized effect on both performance and cost, and a configuration that made sense at launch often doesn't fit how the product evolved.
Cache invalidation is the real design problem
The hard part was never caching content — it's correctly invalidating it when the underlying content changes. A cache policy that's too aggressive serves stale content; one that's too conservative barely caches anything. Getting this right requires understanding how often each type of content actually changes.
Dynamic content deserves a strategy too
It's tempting to treat CDN as purely a static-asset tool, but caching strategies for personalized or dynamic content — partial caching, edge computation, smart cache keys — can meaningfully reduce origin load and latency, if they're deliberately designed rather than left as an afterthought.
Revisit it as traffic patterns change
A CDN configuration tuned for the traffic pattern at launch may be poorly suited a year later, once usage has shifted geographically or the content mix has changed. Treating it as a one-time setup instead of an evolving piece of infrastructure leaves real performance and cost on the table.
- Cache invalidation, not caching itself, is the hard design problem.
- Dynamic and personalized content deserves a deliberate caching strategy too.
- Revisit CDN configuration as traffic patterns evolve, not just at launch.
Database read replicas: when they solve a problem and when they hide one
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