CDN performance
25 Feb 2019

How to Test Your CDN’s Performance

CDN performance is a vital metric. After all, the primary purpose of subscribing to a Content Delivery Network (CDN) service is to enhance the user experience of your site visitors. By improving the page load times of your website, you not only improve customer satisfaction but also gain a crucial advantage in Search Engine Optimization (SEO). Although CDNs do offer other benefits such as load balancing and reduced bandwidth costs, speed and performance are the core services these platforms provide. However, measuring CDN performance may seem straightforward, but the reality is that it is not that easy. There are various metrics and nuances to consider as multiple protocols, both on your site and the network, influence your CDN’s ability to deliver the performance you need.

CDN Performance Benchmarking

The best way to ascertain the impact your CDN has on the performance improvement of your website is to test your page load times without it. By removing the CDN from the equation, you can check the real impact it has on your website’s speed. Although this process will involve making some infrastructure changes to your site’s configuration, by testing load times when your web server is managing requests without a CDN, you can benchmark the performance of your site. It will also help you determine how much load your web server can handle, another vital metric you need to consider for site performance and cost. Once you have ascertained your site speed and web server load threshold, you can then reconfigure your CDN service and rerun the same tests. With the CDN back in service, you should see a significant improvement in all performance metrics.

Monitoring Calls to Your Origin Server

Another metric you can use to determine your CDN performance is to measure how many calls your origin server handles. An optimized CDN architecture should see your origin server managing very few direct calls as the CDN should be serving the majority of your visitor traffic. If your origin server is measuring a high number of HTTP requests, it could point to a misconfiguration in either your web application or CDN. If calls from a web browser are bypassing the CDN and contacting your web server directly, it could point to a misconfiguration in either your DNS or how you have configured the web assets on your server. During your CDN performance testing, you should also check how many calls the CDN is making to the origin server for refreshed content. By optimizing your CDN’s performance, you can reduce the number of HTTP requests to your origin server, significantly increasing your page load speeds and improving your CDN cache-hit ratio.

Test CDN Performance from Multiple Locations

The only way to truly test your CDN is to measure page load speeds from multiple locations. By their very nature CDNs offer a distributed architecture with numerous nodes in various parts of the world serving users in their different geographical regions. As a result of this dispersed platform, users in some parts of the world may experience faster load times. By testing CDN performance from multiple locations, you can ascertain whether your service has the optimal configuration. If a particular area shows higher latency and lower page speeds, it could point to a CDN misconfiguration. As a CDN provides a standard service to each node, the performance in each location should be similar. If this is not the case, the result may be that the origin server is processing too many direct HTTP requests when the CDN should be serving this user traffic.

Test Multiple Protocols

The HTTP protocol has seen a few changes over the years. Released in 1999, HTTP/1.1 remained the standard for 16 years until the publication of HTTP/2 in 2015. With HTTP/3 just around the corner promising faster load times and improved encryption support, website operators have multiple options to consider when choosing the protocol they support on their web servers. These days most CDNs offer HTTP/1.1 and HTTP/2 support. As the dynamics of each version differ, it is vital that you test each standard to determine your CDN performance. In addition to testing HTTP, you should also assess your CDN’s capability in managing secure traffic over HTTPS. Testing your CDN’s support for these multiple protocols gives you the ability to rapidly ascertain how well your chosen provider manages these various web standards. It can also help you quickly identify any potential misconfigurations.

Assess CDN Performance Regularly

Testing the performance of your CDN requires a regular assessment. Like every other process that involves discovery, measurement, and adjustment, the only way for you to ensure your CDN performs as it should is to assess it on a consistent basis. Regular testing can help you identify any issues that may have arisen since the previous assessment. It also enables you to determine the baseline performance of your CDN giving you the ability to detect any anomalies rapidly. For example, should you suddenly notice that your origin server is serving more network traffic than it should, it could indicate a configuration change on your CDN. In addition to identifying possible issues, regular testing can also help you fine-tune your CDN. As the variables that determine CDN performance are continually changing, frequently assessing the multiple aspects that influence page load times can help increase the efficiency of your site, server, and CDN.

Gain Vital Visibility

Testing the performance of your CDN is vital. Content Delivery Networks promise increased bandwidth, a global server footprint, and cutting-edge delivery. Leveraging technology, they not only provide website operators with increased speed but also offer other benefits such as load balancing and reduced operational costs. However, unless you test your CDN regularly, you may not be getting the peak performance this platform has to offer.

Benchmarking your CDN by examining page speeds with and without a CDN is a vital first step in the testing process. It gives you visibility on the performance enhancement a CDN offers. It is also essential to continuously monitor the calls being made to your origin server. If multiple HTTP requests are hitting your site directly, it could point to a CDN or web server misconfiguration. Checking your CDN performance from various locations and examining its throughput using different protocols can also help you gain the comprehensive insight you need. Finally, it is vital that you conduct these assessments regularly. It ensures you not only get the most out of your CDN service but also gives you visibility into any anomalies that may impact the performance of your site.