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How to do an effective trial with a CDN

Tip: Dummy Origin, our free and open source tool, makes it easier to evaluate the (caching) behavior of a CDN. Read CDN behavior testing with Dummy Origin

When you are in the process of deciding which CDN to use, at some point in the selection process you will have a shortlist of 1, 2 or 3 CDNs that are serious candidates. These CDNs meet your key requirements and you had positive conversations with them. As mentioned before in my article How to Select a CDN, the next step is to do a (free) trial with those Content Delivery Networks. This is a key step in the decision making process and one you must never skip.

Goals of the trial

In my opinion, the goal of the trial is simple: be in a better position to decide which Content Delivery Network to sign up with. Doing a trial is all about gathering real experience in using the CDN and working with that particular CDN company. We strongly recommend to free up enough time for the trial, so you can truly answer the following questions afterwards:

  • Does the CDN do what I want/expect?
  • Is it easy to use?
  • Is it fast?

Let's start with a few tips on how to do the trial, the approach to take.

Approach to the trial

Let me repeat: free up enough time to do the trial. It is very important, so don't do it in your spare time. Focus on the important stuff.

Create the evaluation document, in which you will log your findings. Put all your requirements in a 3-column table: Requirement, Score, Remarks. For Score, put in either a -1, 1, 3 or 5, with -1 meaning "not available", 1 meaning "bad", 3 meaning "ok" and 5 meaning "excellent". Remarks is a free text field to write down any relevant notes, probably to help later remind you why you gave that score. After the trial, you can calculate the total score for each CDN.

Create a real-world test page (e.g. a copy of your homepage) and switch on the CDN for that. Even better: use your real site. This may be a bit risky, and if you decide to do this, make sure you are closely monitoring website performance.

Set up the CDN. Configure it to do what you want, e.g. turn on Gzip compression, create the custom CNAME, etc. The CDN provider should play a (pro-)active role in this, advicing you on what is best, of course taking your requirements as a starting point. Involve them!

Use the CDN! Make changes to the config, view and analyze reports, etc.

Evaluating Functionality

You should carefully evaluate all the functionalities/features that you have listed in your requirements document, using the above mentioned evaluation document.

In my opinion, the following should definitely be in scope:
  • Online control panel: ease of use, responsiveness, look & feel
  • Change propagation time: how fast is a change implemented on the CDN platform/edge servers?
  • Security: is the online control panel secure? do you get a different password for FTP?
  • Reports: relevance of data, delay, ability to export data (as CSV)

Evaluating Customer Service

If you need help, you want to get it in a swift, pleasant way, with a satisfying result. Be sure to evaulate these aspects of customer service:

  • Choice of contact method/medium (phone, email, online ticketing)
  • Responsiveness
  • Quality of the response
  • Friendliness
  • Costs: can you call a free or local number?

Tip: contact the customer service department often, not just once. And don't talk to the same representative every time, but talk to several.

Evaluating Performance

As improving performance is the #1 reason to start using a CDN, evaluating performance during a trial is very important. And it is also difficult to get a grip on. Some Content Delivery Networks will play a role in this. Cotendo for example provides Keynote performance reports, free of charge, which is nice.

One thing you can do, easily and for free, is run web page performance tests using on that test page. Do it often and from from various, relevant geographical locations.