Delivery Architecture
Edge Caching
Reviewed by Shalabh Agarwal · OTT & StreamingLast updated: 2026-07-01
Edge caching stores copies of video segments on CDN servers close to viewers, so playback is served from a nearby edge instead of the distant origin. It cuts latency and rebuffering while offloading traffic from the origin.
Enveu take
Edge caching is the quiet workhorse of streaming economics — a high edge hit ratio means fast playback and a small origin bill, which is why cache strategy is as important as encoding.
StreamingCDNDelivery
Where it fits in the OTT stack
Origin→CDN Edge (cache)→Player→Viewer
How it works
- A viewer requests a segment from the nearest CDN edge.
- If cached (hit), the edge serves it immediately.
- If not (miss), the edge fetches from origin, then caches it.
- Subsequent viewers are served from the edge cache.
Key components
- CDN edge servers near viewers
- Cache keys and TTLs
- Origin shield / mid-tier caching
- Cache-hit-ratio tuning
Performance impact
- Lowers latency and rebuffering
- Offloads traffic and cost from origin
- Popular content benefits most from caching
Common issues
- Low cache hit ratio hammering origin
- Cache keys mis-scoped (per-session leaks)
- Long-tail content that rarely caches
When it applies
- Scaling delivery for large audiences
- Reducing origin load and cost
Signals to monitor
- Edge cache hit ratio
- Origin egress
- Time-to-first-byte
Real-world example
Lifting cache hit ratio
Origin load spiked during popular releases.
Challenge
- Low edge hit ratio hit the origin hard
- Latency rose under load
Action taken
- Tuned cache keys and TTLs; added an origin shield
- Optimized segment caching for popular content
Outcome
Edge hit ratio rose, cutting origin load, cost, and latency.
Frequently asked questions
What is edge caching?
Edge caching stores copies of video segments on CDN servers close to viewers, so playback is served from a nearby edge instead of the distant origin, cutting latency and rebuffering.
How does edge caching reduce cost?
When content is served from the edge cache (a cache hit), it doesn't fetch from origin — offloading traffic and reducing origin egress cost, especially for popular content.
What is cache hit ratio?
The share of requests served from the edge cache rather than fetched from origin. A higher hit ratio means faster playback and lower origin load and cost.
What cache hit ratio should I aim for?
Above 90% for VOD is a reasonable target and above 95% is achievable with good cache-key hygiene. Every point below that is extra origin egress, higher cost and slower delivery.
Why do cache hit ratios drop?
Usually cache-key fragmentation — query strings, unnecessary personalization in URLs, or inconsistent segment naming making identical content look unique. Very short TTLs and long-tail catalogues also reduce hit rates naturally.
Build it with Enveu
Deliver from the edge
Enveu streams via multi-CDN with edge caching to keep playback fast and origin costs low.