How to compare CDN services?

Question

What are the metrics and their priorities to compare various CDN services?

Answer 1

The main metrics would be:

• Price.

• Performance. This further breaks down to small-file performance (where latency, i.e. time to first byte dominates) and large-file performance (where transfer rate dominates). Obviously, actually measuring this is darn hard, but here are some decent benchmarks to get you started.

• Geographical coverage for the regions you're interested in. Fx Akamai has > 65.000 servers worldwide and covers pretty much all continents except Antarctica; whereas MaxCDN doesn't have servers in Asia (yet).

• Does the provider offer "Push" CDN zones, "Pull" zones, or both. Which do you want?

• Does the provider offer streaming media zones (video/audio). Do you need this?

• SSL. Not all providers support SSL / HTTPS. Of those who do, not all support SSL together with 'vanity domains' (cdn.yourcompany.com).

• HTTP compression. Good CDNs allow for flexible control over HTTP compression (for much faster download of CSS, JS, and other text files). Amazon Cloudfront is the only exception I can think of right now.

• Reporting. Good providers have great statistics, which help you get visibility into how your content is consumed. Smaller providers often have less extensive stats & reporting.

• SLA's, for those who need this.

• Does the provider offer Edge Side Includes, if you need this.

• Does the provider offer some sort of token-based authentication (f.x. if you want to provide fast download of a software installer file, but won't allow download before the end user has paid for it).