Content Delivery Networks

Content Delivery Networks are a global network of servers stored in data centres around the world. Their purpose is to help serve content to users at improved speeds. The term is commonly abbreviated to CDN.

CDNs are designed to compliment your hosting setup, not replace them. Many hosting companies offer a content delivery network to their customers so that their customers enjoy faster page loading times.

How Do Content Delivery Networks Work?

The server in which you host your website is sometimes known as the origin server. When visitors want to access a web page from your website, they need to retrieve files from this server.

Every element of a web page has to be retrieved and returned to the visitor. This includes text, images, Javascript, and CSS etc. The further a visitor is from your origin server, the longer it takes to retrieve all of these elements. This means that visitors who are close to your origin server should load your web pages quickly, but visitors from a different continent will experience much slower load times.

Content delivery networks address these issues.

They reduce the number of requests from a server by making a static HTML version of every page on your website. This reduces the number of requests necessary to retrieve a web page’s information dramatically; which in turn reduces the time it takes to load a page.

Copies of the cached version of your website is distributed to the CDN’s global network of servers. When a person visits a page on your website, they are redirected to the closest server in that global network. They do not have to go all the way to the origin server.

CDNs also take advantage of other performance techniques such as Gzip compression, expire headers, browser caching etc.

Most companies use what are known as pull zones and push zones.

The pull zone is the content which the CDN retrieves from your website automatically to make a cached version of your website for visitors.

The push zone allows you to upload files directly to the CDN. They are used to distribute larger files to visitors such as documents, video files, audio, and image galleries.

Content delivery networks charge by bandwidth. Most charge per GB of bandwidth used. This rate reduces once you have reached a certain level of bandwidth. Pricing also depends on the geographical area the bandwidth was used.

For example, Amazon CloudFront charges $0.085 per GB of data transfer in the USA and Europe for the first 10TB of data transfer. This rate is reduced to $0.080 for the next 40TB of bandwidth and $0.060 for the next 100TB.

In contrast, Amazon CloudFront charge $0.250 per GB of bandwidth used in South America for the first 10TB. This is reduced to $0.200 for the next 40TB of bandwidth and $0.180 for the next 100TB.

Content delivery networks take all the traffic load off your server. This allows them to deliver quicker page loading times and handle traffic spikes. You therefore never need to worry if a page on your website hits the front page of Reddit and is flooded with traffic.

Since CDNs keep a cached version of your website, they can continue to deliver a static copy of your website to visitors when your origin server is down (i.e. the server where your hosting company stores your files).

The total monthly cost of using a content delivery network will depend on the amount of bandwidth you use. On the bright side, using a content delivery network will greatly reduce the bandwidth costs your hosting company would have charged you. CDN prices tend to be much lower than the bandwidth rates that hosting companies charge; therefore your overall cost should be lower.

With search engines such as Google ranking websites that load quickly higher than those that do not, all website owners need to make website performance a priority. Without doubt, the quickest and most effective way of improving the speed of your website pages is to use a CDN.

Content Delivery Networks

Below you will find a selection of the most popular content delivery networks that operate online.

	Amazon CloudFront Amazon CloudFront has a great reputation online. This perhaps explains why so many hosting companies use it to power their own in-house CDN applications. The service is also used by large websites such as IMDB and SEGA. Their network spans thirty-eight locations across the USA, Europe, Asia, Australia, and South America. Pricing starts from as low as $0.085 per GB and drops to as low as $0.020 per GB for power users.
	CDN.net CDN.net provide a large content delivery network across eighty-eight cities across the globe. Pricing depends on the regions you need to target. They offer three plans at $100 per month. If you target the USA, Canada,and Europe, you will receive 10TB of bandwidth. If you expand to Mexico, the Middle East, India, and Asia, you will receive 5TB of bandwidth. The last option allows you to access the full global network, but it reduces bandwidth to 2TB.
	CDN77 CDN77 are a content delivery work that has thirty-one data centres across the world. They have a great presence in Asia and in South America. Their prices start from only $49 per terabyte of data for North American and European traffic. Their service has a great responsive user interface and integration support for popular content management systems such as WordPress, Drupal, and Joomla.
	CloudFlare In addition to mitigating DDoS attacks, CloudFlare offers a content delivery network that spans seventy-four locations across the world. What may surprise you is that their CDN service is free. You are never charged for the bandwidth you use. If you opt for their Pro plan you will get additional performance features. Their pro plan retails at $20 per month plus $5 for any additional website you want the extra features for. I have used CloudFlare as a CDN for my websites over the last few years and have been fairly pleased with their service. One thing I would say, however, is that their “Always Online” feature does not work well. Therefore, when my origin server has been down, they have not correctly delivered a static copy of my website. This is something that other content delivery networks seem to handle better.
	Fastly A professional CDN that is used my many large websites and organisations. Its network spans across the world and they are adding new locations in Asia and Africa over the next few years. Their rates start at $0.12 per GB for the first 10TB and then reduce to $0.08 per GB.
	KeyCDN KeyCDN is a content delivery network with a network that spans across North America, Europe, Asia, and Oceania. They have data centres planned for South America, Africa, and the Middle East. They offer a user-friendly dashboard and interface and can boast of being one of the cheapest CDN services online. Their rates start at only $0.04 per GB for the first 10TB. That is more than half the cost of Amazon’s CloudFront service. Rates eventually drop to only $0.01 per GB for power users. KeyCDN is a network I am familiar with because I reviewed it in 2015 for this blog and because my good friend and Rise Forums regular Brian Jackson works with the company. If you have any questions about the service, please drop by Rise Forums and start a new thread and Brian will be happy to answer any questions you have about their service.
	MaxCDN MaxCDN is a popular CDN service that is used by many bloggers. Their service is easy to use and their global network of data centres is boosted by peering partners such as Comcast, Verizon, and Vodafone. Rates start at $0.06 per GB for under 50TB of bandwidth.
	Microsoft Azure Microsoft Azure has data centres in twenty-two regions across the world. As you would expect from a company such as Microsoft, their network is robust, secure, and reliable. Pricing starts at around $0.09 per GB of bandwidth for the USA and Europe.