[joshenders]

Absolutely. If you were a CDNs only customer this may be true but the reality is that you’re not and they are always going to be over-subscribed. Having worked at a CDN provider (Cloudflare), I can tell you that they are constantly battling resource contention via DDoS or other reliability issues.

Multi-CDN is the way to go for performance and availability, though as a customer it can be challenging because you’re forced to limit your configuration to the lowest common denominator of features and there’s not a great way to test consistency of your configurations across all vendors.

This article is essentially a high level sales pitch though; I didn’t find it all that useful. I implemented multi-CDN at Pinterest using Cedexis (DNS based), though with modern DNS providers like NSOne, Cloudflare, Dynect, a modern spark-based ETL pipeline, and the browser navigation timing API (RUM), it wouldn’t be too challenging to build something resembling Cedexis yourself.

[eldod]

Indeed the article is more an introduction to multi-CDN concepts, but take into account that it was written for the HTTP video streaming use-case, and not static content CDNs. A client-side implementation of switching would not be very useful for that kind of content.

For Cedexis, I think the strenght is not only in the configurable DNS routing system, but also because they set up a lot of probes for different CDNs & clouds, and share global aggregated data that anyone can access, which can be useful when you don't a Alexa top1000 traffic.