How to understand Content Delivery Networks

This is a first part of the guest post created by Will Vuong. Second part is about pricing and support.

Selecting the Right CDN Ė What You Need to Consider

Companies across all industries turn to CDNs (content delivery networks) to accelerate the delivery of websites and/or web applications across the internet that are critical to their business. Through an interconnected system of PoPs (Points of Presence), CDNs provide a more streamlined and faster delivery method than the standard internet, drastically reducing load time and improving the end user experience.

There are many CDN providers, each offering different solutions, features and performance levels. How do you know which one is best for accelerating your web performance? Here is a list of considerations that will help you select the right CDN.

Network Size and Reach

Undesrtanding content delivery networks

A CDNís 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). For instance, if you are trying to reach China with your origin from the UK, you would probably want a CDN with PoPs located inside the Great Firewall and not in nearby locations outside (e.g. Hong Kong or Taiwan).

When evaluating a CDNís 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 more reliable as it can easily scale and maintain consistent performance during traffic surges and heavy loads.

Caching vs. Dynamic

Understand the difference between caching and dynamic acceleration. Caching is the process of duplicating static web content on PoPs located near end users. Upon request, the duplicated content is served directly from the nearest CDN PoP and not from the origin website, reducing the distance of delivery. A standard blog is an example of a static site, all visitors are served the exact same content and nothing is generated on-demand based on user interaction.

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 etcÖ Dynamic acceleration provides a more direct and faster delivery path (middle mile) between the origin server and end users. Unlike delivery through the standard internet, 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 Ė Difference between caching and dynamic acceleration.

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 CDNís ability to maintain consistent performance throughout the network even during surges of traffic. Reliability is how well a CDN can maintain up time and prevent outages.

It is important to consider all three components when evaluating a CDNís 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 assessment/test to properly evaluate a CDNís performance. Request scenarios specific to your business to be simulated to ensure the CDN is in fact capable of eliminating all current and potential web performance heartaches. It also wouldnít 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 may or may not be essential to your needs. Integrated features may include (not limited to):

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 may not need or you could end up saving by not having to integrate third party tools that are included in your CDN service.

This is the end of the first part of the post about understanding Content Delivery Networks. Second part of the post will be published later this month. Subscribe for updates!

Will Vuong is a web enthusiast and is naturally curious about all things technology and design. He is also a digital marketer specializing web communications and search and is currently leading these efforts at CDNetworks. Connect with Will at Google+ or tweet him at @willv

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