Why Use More Than One
A single CDN is a single point of failure and may be slow in some regions. A multi CDN setup spreads traffic across two or more providers.
What You Gain
- Resilience because if one provider degrades, traffic shifts to another
- Better coverage since providers are strong in different regions
- Price leverage by steering volume to the cheaper provider
- Higher performance by routing each user to the fastest CDN for them
How Steering Works
A traffic director, often DNS based or a steering service, decides which CDN serves each request. It uses real user measurements of latency and availability to pick the best provider, and can fail over within seconds.
Costs
- More complexity in config, purges, and certificates across providers
- Consistency challenges since each CDN caches independently
- Observability must span all providers
Key idea
A multi CDN strategy routes users across several providers via a measurement driven traffic director, gaining resilience, reach, and price leverage at the cost of added operational complexity.