How to Choose a CDN

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Improve Website Performance and User Experience

Introduction ���������������������������������������������������������������������������������������������������3

How Does a CDN Work? �����������������������������������������������������������������������������5

The Most Important Factors to Consider When Shopping for a CDN ���7

Questions to Ask When Selecting a CDN Service ������������������������������������9

CONTENTS

WHAT IS A CDN?A content delivery network (CDN) improves a website visitor’s experience by helping the site load faster and run more smoothly. Many high-volume sites and critical web applications use a CDN to improve performance and overall stability – but that doesn’t mean a CDN is only useful for these high-volume sites. Pretty much any business that relies heavily on its website stands to benefit from a CDN. This e-book takes a look at how CDNs work, how they can benefit your organization, and how to select the right CDN for your business.

WHY DOES MY BUSINESS NEED A CDN?If your business relies on its web applications for critical business needs, a CDN will significantly improve both reliability and function.

A CDN is useful if you have large volumes of content, your content loads slowly, or you want to reduce the cost of server resources. Your business may also need a CDN if you’re interested in capturing more valuable analytics on user behavior or if you want to protect against distributed denial of service (DDoS) attacks and other security exploits.

It’s also important to note that CDNs are transitioning from “nice to haves” to essential tools. According to Cisco’s Visual Networking Index (VNI) initiative, it’s projected that roughly 64 percent of all of the world’s internet traffic will be routed through a CDN by the year 2020. This means that, by not utilizing a CDN, you may very well be putting yourself at a competitive disadvantage.

INTRODUCTION

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WHAT ARE THE BENEFITS OF HAVING A CDN? There are a number of ways in which a CDN can help your business. A CDN…

Improves page load times and the overall responsiveness of your site. With a CDN, visitors to your site will enjoy faster page load times, speedier downloads, and an overall better user experience. Since users are less likely to get frustrated with long page loading times, they more likely to stay on your site (and purchase items or transact business).

Keeps your website up and running smoothly. CDNs can help mitigate sudden spikes in traffic. So, for example, if you have an e-commerce website and you see a dramatic, unexpected jump in site visits due to a sale, you don’t have to worry. The CDN will ensure that your site can handle the traffic.

Helps improve your website’s search engine optimization� Page load time is a ranking factor for search engines like

Google. Reducing your site’s page load time can therefore increase your ranking on search engine result pages.

Provides significant security benefits. Content delivery networks with a security component can protect your site against a DDoS attack and malicious hackers.

How much your business can benefit from a CDN depends on a number of factors, including how much media your website uses and the CDN provider you choose. To better understand your choices, knowing how a CDN works will equip you with the information you need to make a decision.

A CDN improves your website user’s experience by bringing your content closer to them.

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The core benefits of a CDN rely on how it is structured and how it operates. The theory behind CDN operation is simple, the technology it uses is complex.

A CDN provides a third-party layer between your content and your user. Structurally, a CDN is an aggregate of multiple tools that are used to optimize your website and deliver it quickly to your visitors. A CDN will provide:

1� Caching. Snapshots of websites are saved at intervals and then served up immediately to users through the faster and more responsive CDN network. Caching primarily works for pages that are static, but for those pages, they can greatly reduce bandwidth and server resources. Caching also works for images, video, and other content that do not change.

2� Minification. Minification is designed to compress scripts such as JavaScript and HTML in a way that is still machine-readable but not necessarily human readable.

Most programmers try their best to write code that is easy to update, which can make it far lengthier than it has to be. Minification essentially “trims the fat” from this code. This saves a tremendous amount of data, as only the compressed scripts are sent from the server and processed by the user’s browser.

3� Front-end optimization. In addition to minification, the CDN will also ensure that the website utilizes the visitor’s resources in a way that is most effective. Front-end optimization displays the page effectively so that it requires less processing by the user’s browser. This takes some of the burden off of the front-end developers to optimize the graphics and other elements.

4� Mobile optimization. Sites that are displayed on mobile devices don’t need to take up the same amount of resources as a site that is displayed on desktops. CDNs can optimize sites for mobile usage so that visitors to your site still have the same experience but are less of a drain on your resources.

How Does a CDN Work?

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As an example, images don’t need to be the same resolution when being transmitted to a mobile device. Mobile optimization also provides benefits to the end user because they can view sites even on older phones.

5� Security functions. CDNs provide several valuable security functions. For example, they can utilize SSL technology to encrypt the data that is sent between users and the server. This encryption ensures that data cannot be viewed by malicious outsiders. CDNs can also protect against denial-of-service attacks, by identifying them and refusing to serve the malicious requests. Finally, CDNs can monitor traffic for suspicious activity — advanced CDNs can work hand-in-hand with threat detection solutions. Because CDNs sit in front of your network, they provide the first line of defense against malicious traffic and requests.

A CDN aggregates multiple tools to optimize your site and improve content delivery.

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Once you know the inner workings of a CDN, it’s time to evaluate your potential providers. There are an incredible number of CDN service providers, but finding the right one hinges on a few major criteria:

• Performance. Some CDNs are better suited to serving static content. Other CDNs are better suited to serving dynamic content. Some CDNs simply have more resources than others, while others have more advanced technology. The actual performance improvement of your website through the use of a CDN is extremely important. You may need to try out multiple CDNs before settling on one. Ask your provider for speed comparisons and optimization tests.

• Geolocation. The closer your CDN is to your core audience, the better it will perform. Find out how the CDN is structured – which is it: a scattered or consolidated/

unified CDN? Look for a data center close to the majority of your users or one that has Tier 1 peering agreements.

• Reliability. When a CDN goes down, so does your website. As a result, your CDN needs to be even more reliable than your web service. The ability to use multiple, redundant CDNs can ensure your website’s availability. Your CDN should be able to report on its reliability and explain any significant downtime that it has experienced in the past. Ask your provider for its SLA on availability.

THE MOST IMPORTANT FACTORS TO CONSIDER WHEN SHOPPING FOR A CDN

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• Scalability. If your CDN isn’t able to scale for increased traffic quickly, you may find yourself unable to deliver content during critical, high volume times. CDNs are designed specifically to protect against these high traffic times by providing additional resources. As your web application grows, you will also need a provider with more resources. If your website isn’t scalable, you may need to switch your current CDN provider or get one that will allow you to grow.

• Responsiveness. When it comes to CDNs, its responsiveness is associated with latency. Latency is defined as the amount of time it takes for the server to respond to a query, rather than the amount of time it takes for the server to return all of its content. Both responsiveness and speed are important: 47percent of users expect a website to load completely within two seconds.

• Cost. Finally, your CDN needs to fit your budget. Everyone can always pay for more power and more speed – but there’s no point in paying for more than you realistically

need. You’ll need to determine how much your website will benefit from a CDN versus the total cost of implementation and on-going resources for maintaining it.

A CDN’s technology stack lets it scale and stabilize performance during times of high traffic.

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When comparing multiple CDN services, there are some essential questions that can highlight the differences between your options. Pose these questions to your provider to identify the best solution for your business.

1� How will this CDN improve my website’s security? Your CDN provider should be able to outline the steps that it takes to improve the security of your site, including the use of advanced two-factor authentication services, government-grade encryption standards, and the physical security of their premises.

2� What sort of presence does the CDN provider have with major internet exchanges? Through better infrastructure and peer-to-peer relationships, CDN providers can provide faster, more reliable, and direct connections. CDN providers accelerate their traffic by connecting through their peering agreements, providing improved

performance, better routing, and higher levels of security.3� What type of peering agreements does the CDN provide?

Does the CDN rely on public peering points for its data exchanges, or is it able to negotiate directly with ISPs? How does it establish its connections from the server to your users? Does it have Tier 1 peering agreements?

4� What sort of topology does the CDN use? Though it isn’t the only factor to consider, the topology that a CDN uses can impact its cost. A scattered CDN will have many separate service centers distributed throughout a region, which minimizes latency but increases cost. A unified CDN will have a single, large, and connected infrastructure, which offers lower maintenance costs but can be slower in areas with low connectivity.

5� What type of analytics data does the CDN provide? CDNs provide very valuable traffic analytics, regarding when your site is accessed and which demographics are

QUESTIONS TO ASK WHEN SELECTING A CDN SERVICE

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accessing it. Though you may have other services available for your statistics, these analytics can also become a very important competitive advantage.

6� Can I use more than one CDN? There are many advantages to using redundant CDNs. Incapsula is one service that lets you add another CDN on top of it, thereby increasing the reliability and speed of your system. Other CDNs may require that you only utilize a single network at a time. Using additional CDNs will protect against your site going down and will provide additional resources for periods of very high traffic.

7� What does their SLA (service-level agreement) offer? A service-level agreement outlines the guarantees and assurances the CDN can offer, in addition to remedies in the event that it is not able to operate up to these standards. You should question SLAs that appear to be too good to be true, as they often are; every system will fail occasionally, and if they say that they never fail, they are likely excluding data.

CHECKLIST FOR CDN PROVIDERSYes No Does CDN offer���

Website securityFacility redundancyPeering relationshipsTier 1 agreementsCDN topology: Scattered / unifiedMonitoring and reportingMultiple CDN capabilitiesSLA: 99.999, 99.99, 99.9

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CONCLUSION

A CDN is a necessary tool for many organizations, especially online businesses. CDNs provide a variety of benefits: they increase the speed of your content, improve the reliability of your services, and even bolster your security. CDNs are virtually invisible to your users, thereby offering these improvements without any negative impact to user experience. However, because a CDN needs to provide a vital third-party layer between the content and the user, it also needs to be selected very carefully.

Many businesses that rely on their online content can benefit from a CDN. E-commerce sites, in particular, have more need for the speed, reliability, and security that a CDN can offer. Organizations that have a web presence will find a CDN beneficial in improving website availability and efficiency. It all depends on how much an organization depends on their web applications – and how much traffic they truly need to support.

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