Selecting the Right CDN – What to Consider

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Anyone who manages a website has probably heard of a content delivery network (CDN). For those who haven’t, here is a great article that explains the ‘what’ and ‘how.’ You can also watch this short video for a more technical explanation on the benefits of using a CDN.

The primary benefit of using a CDN is it drastically reduces load time, making your website faster and more responsive. A fast loading website is becoming more important, as it is essential for everything from optimizing user engagement to improving SEO rankings.

There are many CDN providers (I personally work for one), each offering different solutions, performance levels and features. How do you select the right CDN for accelerating your website?

All websites are different in functionality, the type of content it serves and the geographical region(s) it caters to. There are several factors that must be taken into consideration in order to select right CDN for your needs:

Caching vs. Dynamic
Understand the difference between caching and dynamic acceleration. Caching is the process of duplicating static web objects such as standard html, CSS files, JS files etc… and serving it from CDN servers (PoPs) closest to the end user. This process reduces the distance of delivery, therefore reduces load time.

However, caching alone may not be sufficient if your website serves up dynamic content. Unlike static content, dynamic content is real-time data and personalized content generated on-demand and served from the origin server. Dynamic content is typically served from interactive websites such as online gaming, applications, online trading etc… Dynamic acceleration provides a more direct and faster delivery path (middle mile) between the origin server and end users. Unlike standard internet delivery protocols, data packets are required to travel through less connecting points and larger volumes can be delivered simultaneously.

Most CDNs provide caching services, but very few provide dynamic acceleration. Understand the type of content you are delivering. If it is purely a static site, caching alone may be sufficient. If you intend on accelerating an interactive website or interactive components on your site, a combination of caching and dynamic acceleration may be required.

Short Video – Difference between caching and dynamic acceleration

Network Size and Reach
A CDN’s network size and reach is determined by the number and location of PoPs. A large number of PoPs located in many different regions may be ideal for reaching a globally disbursed audience, but it may not be the right CDN for you if it does not have a presence in your targeted region(s). A CDN may have thousands of PoPs in North America and Europe, but it does you no good if your end users are located in Asia.

When evaluating a CDN’s network, find out if it has PoPs in your targeted regions. The closer a PoP is to your end users, the lower the latency (time required to deliver web content to the client). If no CDNs have PoPs located in your targeted regions, go with the one that has the closest PoPs.

Once you have selected the CDN with the reach you require, evaluate the size of the network and the number of PoPs it has in each region. Larger networks with more PoPs are typically more reliable as it can easily scale and maintain consistent performance during ‘traffic spikes.’

Performance
The three primary components of performance are speed, scalability and reliability. Speed refers to how fast the network can return the requested content to the end user. Scalability is the CDN’s ability to maintain consistent performance throughout the network in any condition. Reliability is how well a CDN can maintain up time and prevent outages.

It is important to consider all three components when evaluating a CDN’s performance. A quick delivery rate is important, but an unreliable network with limited scalability will potentially present you with a lot of heartache.

The level of performance for each component varies between different CDNs and the key is to find the right balance for your needs. Always request a performance test to properly evaluate a CDN’s performance. Request scenarios specific to your user environment to be simulated to ensure the CDN is in fact capable of eliminating all current and potential web performance issues that you are concerned with. It also wouldn’t hurt to do a Google search on the history of network outages on the CDNs you are evaluating.

Integrated Features
Each CDN offers a different set of integrated features that you may or may not need. Features may include (not limited to):

  • Cloud Storage
  • DNS Services
  • Security
  • Performance management tools
  • Load Balancing Tools
  • SSL

Content acceleration services alone may not always be sufficient for your needs and other integrated features and tools may be required. You may also not need all the features offered by the CDN, depending on traffic requirements and the type of content you are accelerating. Some features may be included and others may cost extra.

The point is to be aware of what features are offered by the CDN and which ones are included or cost extra. Review your current site structure and web performance challenges before deciding which features are essential. You may end up paying for features that you don’t need or you could end up saving by not having to integrate third party tools that are included in your CDN service.

Pricing
Price options vary between different CDNs and it is important that you fully understand what you are paying for. A big price tag does not equal the best performance or the greatest reach. Take the time to evaluate and understand what the CDN has to offer for the price you are presented with.

Also be aware of additional or hidden costs that you may not anticipate. Not all CDNs will have an all inclusive price plan and may require additional cost for the following:

Better Performance – Some CDN’s may place you on the “standard” network and require a premium for the higher performing network.

Features that may be standard with other CDNs – Some features (as mentioned above) may or may not be included in your price plan. Always review what you are getting for the price you are paying

Midgress Traffic – charges for traffic exchanged between PoPs

Burst Traffic – Some CDNs may charge a higher rate for any traffic that exceeds the contractual limit

Support – quality and around the clock support may not always be included in your price plan

Carefully review the pricing structure and know exactly what you may be paying for. Evaluate each and every performance metric, feature and service item to determine if the price point provides you with the best value. The key is not to get the lowest price, but the best price.

There are many factors to consider when selecting a CDN that best fits your needs. Understand what your needs are and focus on providers that satisfy them. Always take the time to evaluate the solutions, features and benefits that makes sense for your website. The point is not to select the best CDN, but to select the CDN that best meets your needs.

Author

Willv

Will Vuong is a web enthusiast and is naturally curious about all things technology and design. He is also a digital marketer specializing in web communications and search marketing and is currently leading these efforts at CDNetworks.

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