7 Reasons to use a Content Delivery Network

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Content Delivery Networks (CDNs) have revolutionized web hosting during the past few years. Rather than hosting your website a single server, you can distribute the files and load across multiple systems.

What Files can be Hosted on a CDN?

Most CDNs are used to host static resources such as images, videos, audio clips, CSS files and JavaScript. You’ll find common JavaScript libraries, HTML5 shims, CSS resets, fonts and other assets available on a variety of public and private CDN systems.

CDN Services

There are a number of free CDNs offered by Google, Microsoft, Yahoo and other large web organizations. For example, few people host their own videos when YouTube and Vimeo offer amazing free services. Similarly, if you require jQuery, you can load it on any page using:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js.js"></script>
or

<script src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.6.4.min.js"></script>
Alternatively, you could use a private commercial CDNs such as Amazon S3, Microsoft Windows Azure
and MaxCDN to host your own files.

The Benefits of Using a CDN

There are several reasons why a CDN could benefit your website and company. 1. Different domains Browsers limit the number of concurrent connections (file downloads) to a single domain. Most permit four active connections so the fifth download is blocked until one of the previous files has been fully retrieved. You can often see this limit in action when downloading many large files from the same site. CDN files are hosted on a different domain. In effect, a single CDN permits the browser to download a further four files at the same time. 2. Files may be pre-cached jQuery is ubiquitous on the web. There’s a high probability that someone visiting your pages has already visited a site using the Google CDN. Therefore, the file has already been cached by your browser and won’t need to be downloaded again. 3. High-capacity infrastructures You may have great hosting but I bet it doesn’t have the capacity or scalability offered by Google, Microsoft or Yahoo. The better CDNs offer higher availability, lower network latency and lower packet loss. 4. Distributed data centers If your main web server is based in Dallas, users from Europe or Asia must make a number of trans-continental electronic hops when they access your files. Many CDNs provide localized data centers which are closer to the user and result in faster downloads. 5. Built-in version control It’s usually possible to link to a specific version of a CSS file or JavaScript library. You can often request the “latest” version if required. 6. Usage analytics
Many commercial CDNs provide file usage reports since they generally charge per byte. Those reports can supplement your own website analytics and, in some cases, may offer a better impression of video views and downloads. 7. Boosts performance and saves money A CDN can distribute the load, save bandwidth, boost performance and reduce your existing hosting costs — often for free. What’s not to like? As you’d expect, that’s not the whole story. Come back soon for 7 Reasons NOT to use a Content Delivery Network

Frequently Asked Questions about Content Delivery Networks (CDNs)

What is the main purpose of a CDN?

The primary purpose of a Content Delivery Network (CDN) is to improve the speed and reliability of web content delivery to users. It does this by storing copies of your website’s content on multiple servers located in different geographical locations. When a user requests your website, the CDN delivers the content from the server closest to the user, reducing the time it takes for the data to travel, thus improving the speed of your website.

How does a CDN improve website performance?

A CDN improves website performance by reducing the distance between the user and the website’s server. By storing copies of your website’s content on servers around the world, a CDN ensures that users can access your website quickly, regardless of their location. This results in faster page load times, less buffering for video content, and an overall better user experience.

What are the security benefits of using a CDN?

CDNs offer several security benefits. They can protect your website from Distributed Denial of Service (DDoS) attacks by absorbing and dispersing the traffic across its network of servers. CDNs also offer SSL/TLS encryption, ensuring that data transferred between the user and your website is secure. Some CDNs even provide additional security features like Web Application Firewalls (WAFs) and bot mitigation.

Can a CDN help with SEO?

Yes, a CDN can help improve your website’s Search Engine Optimization (SEO). Faster websites tend to rank higher in search engine results, and a CDN can significantly improve your website’s speed. Additionally, CDNs can help ensure that your website is always available, which can also positively impact your SEO.

How does a CDN handle traffic spikes?

A CDN can effectively handle traffic spikes by distributing the load across its network of servers. If your website experiences a sudden increase in traffic, the CDN can quickly scale up to meet the demand, ensuring that your website remains available and performs well, even during peak traffic periods.

What types of content can a CDN deliver?

A CDN can deliver a wide range of content, including HTML pages, javascript files, stylesheets, images, and video content. Essentially, any content that can be served over HTTP or HTTPS can be delivered via a CDN.

How does a CDN affect mobile users?

A CDN can significantly improve the experience for mobile users. By delivering content from the server closest to the user, a CDN can reduce latency, resulting in faster page load times. This is particularly important for mobile users, who often have slower internet connections than desktop users.

Can a CDN reduce bandwidth costs?

Yes, a CDN can help reduce bandwidth costs. By caching and compressing content, a CDN can significantly reduce the amount of data that needs to be transferred, which can result in lower bandwidth usage and cost savings.

How does a CDN work with dynamic content?

While CDNs are best known for delivering static content, they can also effectively handle dynamic content. Some CDNs use techniques like dynamic content caching and TCP connection optimization to ensure that dynamic content is delivered quickly and efficiently.

How to choose the right CDN for my website?

Choosing the right CDN depends on several factors, including your website’s traffic volume, the geographical distribution of your users, the types of content you serve, and your budget. It’s important to consider these factors and compare the features and pricing of different CDNs to find the one that best meets your needs.

Craig BucklerCraig Buckler
View Author

Craig is a freelance UK web consultant who built his first page for IE2.0 in 1995. Since that time he's been advocating standards, accessibility, and best-practice HTML5 techniques. He's created enterprise specifications, websites and online applications for companies and organisations including the UK Parliament, the European Parliament, the Department of Energy & Climate Change, Microsoft, and more. He's written more than 1,000 articles for SitePoint and you can find him @craigbuckler.

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