A multi-CDN strategy can help you reduce latency, improve performance and save costs if you can route traffic in real time using the CDN provider that provides the best cost/performance ratio for your business.
The performance of a single CDN often varies by geography, performing well in some regions and not so well in others. This is a function of regional coverage and connectivity of the CDN points of presence (PoPs). Even the best-performing CDNs regularly experience spikes in latency that can last for hours. Global online organizations need their applications to perform well in all regions and at all times. A multi-CDN strategy, including adding regional CDNs where global CDNs' performance is consistently slower, can deliver better performance than one CDN for all.
Some CDNs provide specialized features, such as WAF, static content optimization, or security. By using several CDNs, each with different specialized features, you can use individual CDNs for the type of content or usage scenario they’re best at.
Different CDN providers may have variable pricing for different regions of the world, for peak vs. off-peak hours, volume pricing, etc. By using several CDN providers and diverting traffic to the CDN that provides the lowest cost at a given time or for a given user, you can substantially reduce cost.
Each CDN operates its PoPs differently and may have access to different upstream data centers. At any given time, PoPs in the same geographical location, but operated by different CDN providers, will have different latency. You can benefit by pitting these PoPs against each other and diverting traffic to the PoP that currently provides the best latency.
CDN providers, while they operate large commercial networks, do not have unlimited capacity. Large peaks in traffic may overwhelm your CDN provider. Also, CDNs can experience regional or even global outages. With Multi CDN, in case of a problem you can immediately divert traffic to another CDN which is up and running.
If a CDN is compromised, or taken down by a DDoS attack, it can take out thousands of websites relying on that CDN to deliver content. Having multiple CDN providers reduces this risk, because it’s highly unlikely attackers will take out two or more CDN providers at the same time.