I recently started reading upon CDNs and how they can help optimize web requests by having a network of edge nodes which are much closer to the user.

What kind of parameters do CDN Providers look upon to determine where the edge node should be placed? Will it be just a look up of how many requests come from each region and then place more servers there or are there other factors as well like, maybe Facebook has a lot more requests coming from a particular part of Europe. To help them optimize their requests, a lot of edge nodes may be placed near them?

I realize this is a subjective question, but I am not sure where else I can ask this question!

  • Unfortunately this is far too broad and opinion-based for this site. Questions here are required to be about websites under your control, and this would invite a speculative discussion outside the scope of that. – dan Jan 13 '17 at 0:54

An Edge node is the server that delivers the content to the user. A CDN is typically spread throughout the globe having edge nodes at multiple continents and even multiple Internet Backbones.

The edge node might be an application server, a caching server, or reverse proxy. When you query the CDN, it checks the Edge location which can get you the data with the minimum number of hops. While it optimizes for performance, it then tries to deploy popular data near the client who asked for it.

Just because you're using a CDN will not mean that your data is replicated across each and every node. There are different caching mechanisms that are employed by different CDN networks

You can read more about it here: https://support.rackspace.com/how-to/what-is-a-cdn/

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A subjective answer for a subjective question.

According to my experience, there are multiple factors such as ping time, number of users, cost of facility, user's location etc for CDN companies to determine where to place their edge nodes. After all, if cost is not a concern, CDN providers could had attached their server directly to every ISP in the world to give the fastest response.

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