Ask Penny: What’s a CDN?

Posted By on May 25, 2015 in CraftHack, Creative Business

Welcome back to another round of Ask Penny, where our resident expert answers YOUR tech-related questions! Take it away, Penny!

Ask Penny

What’s a CDN?

A question I’m asked by clients with increasing frequency is – “my host provider says they now offer CDN services. What is it? Do I need it?”

CDN stands for “Content Delivery (or Distribution) Network” and it’s primarily used to help distribute content so that it’s closer to where users need it.

Your web server might be located in a quiet corner of the United States and you need your video podcast to load and play whether it’s for a user just down the street, in New York, London, Tokyo, Sydney, or anyplace in-between. A CDN service will most likely have a global network of servers.

But not all content benefits from this service. It’s important to think about your site and what makes the most sense for you. If you have a web server that is located near to the primary users of the site, you likely won’t gain much when implementing a CDN.

A CDN is really best for image, audio, and video when viewed over a large geographic region; and the parts of a site that don’t change frequently. For example, moving your theme image files (your header and bio images, theme css, and social media icons) may help response times and your pages to load faster.

It’s also helpful in shared-hosting environments when you are already competing with other websites on that server (please see Ask Penny: When to start using a paid website for more about different hosting options).

While this was traditionally expensive, the prices have come down significantly in recent years and competition has further fueled this market.

There are a few questions you need to ask before signing up for a CDN. Just because your host provider offers it, doesn’t mean you have to sign up for it!
1. Where are they located?
2. How is network performance measured?
3. What is the cost and how is that measured? Can that be adjusted at any time?

Once you decide on a CDN, there are many tools available to assist you in configuring it for your site and once you do, it takes care of the magic of moving the files you specify to the service. There are a few caveats: if you change the theme or add new scripts you may need to deal with propagation delay as the cached files are updated throughout the network. If you decide to close your account or the CDN goes out of business you’ll need to remember to update your site configuration so that your images load properly to site visitors.

I hope this brief introduction helps you decide if a CDN is right for you.


Penny Shima Glanz spends her days spinning yarn and code into memorable projects. Small businesses rely on her for practical technology solutions. Designers rely on her to sample, test, and edit their handknit and crochet patterns. She loves muddy trail runs, fosters kittens, and lives in Westchester, NY with her husband and two resident cats.

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