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SMPERF03-BP01 Use a content delivery network and monitor your cache-hit-ratio - Streaming Media Lens
Implementation guidanceResources

SMPERF03-BP01 Use a content delivery network and monitor your cache-hit-ratio

Deploy a content delivery network (CDN) in front of your streaming

origins and monitor cache-hit-ratio per content type to protect the origin and reduce viewer latency.

Desired outcome:

  • You have a CDN in front of every streaming origin, absorbing viewer load at the edge and protecting the origin from traffic spikes.

  • Your cache-hit-ratio is tracked per content type (live manifests, live segments, video on demand (VOD)) and alerts fire when it drifts below targets.

  • Your time-to-first-byte for viewers is dominated by edge delivery, not origin fetches.

Common anti-patterns:

  • Tracking overall CDN bandwidth but not cache-hit-ratio, hiding origin shield failures until costs spike.

  • Invalidating the entire distribution when only a handful of objects need refreshing, instead of targeting specific paths.

  • Running without an origin shield, forcing every edge miss to hit the origin directly.

Benefits of establishing this best practice:

  • Lower time-to-first-byte because viewers fetch from nearby edge caches

  • Less load and lower cost on origin infrastructure during traffic spikes

  • Ability to scale to large concurrent audiences without origin bottlenecks

  • Faster playback start and fewer mid-stream stalls for geographically distributed viewers

  • Clear cost signal when cache-hit-ratio drops, enabling proactive capacity planning

Level of risk exposed if this best practice is not established: High

Implementation guidance

A single aggregate cache-hit-ratio (CHR) number masks important differences between content classes. The 95% overall CHR on a CDN dashboard can hide different per-class behavior. Live manifests might run at 40% hits. Segments might run at 99%. Segments dominate the average because they are requested far more often. Manifest latency affects every viewer directly because the player must fetch a fresh manifest before it can request the next segment. CHR has to be broken down by content class before it becomes a signal worth acting on. CHR also correlates directly with origin cost. At a live event, a one-point drop in segment CHR can multiply origin bandwidth by ten. Every miss fans out to a distinct origin fetch. When you treat CHR as a capacity-planning input alongside a performance metric, drops in CHR can trigger cost alerts before they become billing surprises.

Implementation steps

  1. Deploy Amazon CloudFront as your CDN solution: Set up CloudFront distributions for your streaming content.

  2. Configure cache behaviors for different content types: Set the following:

  • Live manifests to half segment length or less

  • Live segments to 21,600 seconds or max digital video recorder (DVR) window

  • VOD content to 86,400 seconds or longest possible

  1. Enable CloudFront monitoring and metrics: Activate monitoring for visibility into CDN performance.

  2. Monitor cache hit ratio, origin latency, and HTTP error rates: Track key performance indicators for cache effectiveness.

  3. Set up CloudWatch alarms for cache performance thresholds: Configure alerts to detect performance degradation.

  4. Optimize cache-control headers from origin: Verify the origin sends appropriate caching directives for each content type.

  5. Implement cache invalidation procedures: Establish processes for invalidating stale content when needed.

  6. Monitor and minimize negative caching for live content: Reduce the impact of error responses being cached.

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