Originally written by Mark Montaquila at the Catchpoint blog.

When faced with choosing between internal application monitoring and external synthetic monitoring, many business professionals are under the impression that as long their website is up and running, then there must not be any problems with it. This, however, couldn’t be further from the truth.

The need for an external synthetic monitoring tool is actually more important than anything else, because in this world of high-speed, instant gratification (eCommerce site administrators are nodding their heads), if your customers are affected by poor performance, you will not have customers for long.

For a simple explanation of this concept, imagine a fast food restaurant. First of all, out of all of the fierce competition, one needs to make the choice of a specific restaurant. Once chosen, you don’t want to turn business away. So if the door is unlocked, it would mean that the store is open, or in the case of a website, “available.”

Once at the counter, the customer puts in the order, which would be the same as someone going to a website to perform any interaction. These interactions would be the clicks or “requests” within the site. Once the order goes in and as they wait at the counter, the cheeseburger, fries, and apple pie they requested are all delivered in a reasonable and expected amount of time.

However, there appears to be a problem with the drink, because it’s taking longer than usual to get it. Behind the scenes, the drink guy has to change the cylinder containing the mix, and subsequently the drink order takes 10 times longer to be filled. The customer does not know this, and as time passes, frustration grows.

When the drink is finally delivered, the unhappy customer decides to complain to the manager about the speed (or lack thereof) of getting his order. When questioned, each person explains “I did MY job.” This includes the drink guy, whose only responsibility was to deliver the drink as ordered, which in this case, required changing the cylinder. Speed was of no consequence to him, and in his mind, he fulfilled his task to expectations. So from an internal perspective, this is absolutely true. Everyone did their job 100% correctly.

The customer’s (external) perception, however, is a completely different story. To the customer, this was a complete failure and frustrating experience which is sure to tarnish his perspective of the entire brand for the foreseeable future, thus preventing any return for a long time. Even worse, it increases the likelihood of this displeasure being shared with friends on social media, which as we all know can spread like wildfire and irreparably damage a brand.

Hence the importance of monitoring from the outside from the customer’s perspective. This is an absolute necessity in order to avoid customer frustration due to behind-the-scenes problems that slow down web performance and drive away new business.

Whereas internal monitoring provides a valuable – yet incomplete – look at how your site is performing by your own standards, external monitoring can act as a buffer to bad experiences and catch problems before they become an issue for customers. This will keep them happy and satisfied, and more importantly, encourage them to keep coming back.