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Businesses today, even small businesses, often need a global presence. The Internet is the obvious path to that goal, but just because the Internet can reach virtually every spot on the planet doesn’t mean it can always reach those spots efficiently.
Rich content, particularly video, is susceptible to delay and packet loss on long delivery paths; even local content delivery can experience these problems at critical times. It would be nice, but impractical, to have a content server next to every user to ease delivery; content delivery networks (CDNs) are a practical step in that direction.
The biggest misconception about content delivery is that “the Internet” is a unified network. It’s not. It’s a community of interconnected (or peered) independent networks owned by different companies and managed in different ways at both the business and technical levels. When users try to access your content, their requests and your responses may pass through the hands of several, perhaps a dozen or more, of these networks. At any point, they can be delayed or lost.
But the Internet is unified in terms of connectivity. Anyone in the world can reach your content hosts—including people trying to hack them or overload them with requests (i.e., denial of service attacks). If your site is overloaded or hacked, you’re disconnected from your users, and the considerable time and money you’ve invested to gain their attention and trust is wasted.
The why behind content delivery networks
Content delivery networks address these problems in a simple way, by hosting a copy of your content in the same geography as your users are concentrated. This process, called caching, lets users find content without transiting multiple interconnected networks. As a result, your content delivery performance will be better and more consistent for all users within range of a cache point.
Content caches are useful to the extent that they’re close to your prospective users. This means it’s critical to identify the geographic locations where you expect to find users and pick a CDN provider with cache points in the right locations. Where multiple access providers serve the same area, whether mobile or wireline, it may be necessary to understand how each CDN is peered with the access Internet service providers (ISPs) in order to determine whether content experiences for all your target users will be optimized. This is especially critical for mobile content delivery. The mobile networks where your users operate, not the users’ home networks, are the places where CDN support is needed.
CDN protection from denial of service attacks
Multiple copies or caches protect you against hackers. CDN providers protect their caches against hacking, and since multiple copies of content are distributed in multiple locations, a denial of service attack can’t take down all of your content.
All of this happens without action on your part. The CDN provider identifies cache points in your target locations and provides the necessary tools (Web page tools, directory services and so on) to connect your users with the best cache point at a given moment, whether they’re operating from fixed broadband connections or using mobile devices.
New missions for CDN providers
Many CDN providers also host more than traditional video and media content. Some application acceleration facilities build complex Web pages in the cloud and deliver optimized HTML to browsers for better performance. Some provide optimized interactivity features ranging from text chat to voice or even video connections. Over time, it’s likely that CDN features and cloud computing features increasingly will be combined.
Internet Peering creates significant performance variability, more than many users are willing to tolerate. CDNs are the best defense against your users fleeing to other sites because their experience with your site is below par. At the very least, every company with a Web presence involving rich content should check out CDNs.
Content delivery network primer: Why CDNs matter
Preventing CDN security breaches
Video and mobile markets create new opportunities for CDNs