CDNs (CD what nows?)

With the ever increasing demands that come with scale on popular websites, site owners are always looking for ways to move resource demands away from their traffic inundated servers.

There are a number of ways of offsetting or distributing demand, I'm going to cover just one, Content Delivery Networks (CDNs).

Content Delivery Networks are servers which host duplicate copies of a given resource or resources, this might be your site's images, javascript or media.

Why might you need to move your resources to a CDN?

When your browser downloads a web page, it has a limited number of active connections it can make to a domain, typically around 2.

This means that if it's busy downloading images on one, and media on another, you're not going to see the page until both have finished downloading.

Pushing those resources to other domains via a CDN means you get:

  1. More active connections available so the page can load quicker.
  2. Resources can be pulled down from locations geographically closer to the user, resulting in even faster page speeds.
  3. A reduced load on your server, no bandwidth cost on your server.
  4. Duplication of your resources gives you redundancy failovers if servers are down.
  5. Sites that use the same resources, which a user has previously downloaded, will not need to download them again, giving big speed gains.

You can see how there are some immediate benefits to using them.

Want to use one now?

Google and Microsoft have somewhat closed CDNs meaning they won't host your content, but they do host some common files you might need, such as jQuery.

<span style="color: rgb(96, 96, 96);">   1:</span> &lt;script src=<span style="color: rgb(0, 96, 128);">"http://ajax.microsoft.com/ajax/jquery/jquery-1.3.2.min.js"</span> type=<span style="color: rgb(0, 96, 128);">"text/javascript"</span>&gt;&lt;/script&gt;

Or:

<span style="color: rgb(96, 96, 96);">   1:</span> &lt;script src=<span style="color: rgb(0, 96, 128);">"http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"</span> type=<span style="color: rgb(0, 96, 128);">"text/javascript"</span>&gt;&lt;/script&gt;

So why wouldn't you use them?

Cost, there are a whole lot of ways you can customise your requirements, number of servers, redundancy, global availability etc. Akamai, Amazon, CacheFly and Limelight Networks all have offerings in this space.

Having issues with scale or need a high demand, high availability site and need help? contact Compsoft today.