字幕列表 影片播放 列印英文字幕 Content Delivery Network - Transcript Hi, I'm Ryan Sumner I am a Chief Delivery Network Architect with IBM Cloud and today I'm going help you answer what is a Content Delivery Network. So, in short, a Content Delivery Network, or CDN, is a service that accelerates internet content delivery. So, in other words the main benefit of a CDN is that it makes your website faster. So, before I get into describing to you how it accomplishes that and some of the other benefits. First, I want to talk to you about some of the challenges that we have where we have users all around the world, but we don't have servers all around the world and the experience that those users have due to that dynamic. So, I got a simple diagram here showing a server hosted down in Dallas, this is my website, and I have users all around the world. So, in Sydney I might have five, in London I've got five, New York I might have ten, and LA I might have ten. I've thirty users around the world they're accessing my server and my website down in Dallas. So, lets you can follow a set of these users in their journey and let's look at their users down in Sydney. They make a request to the website they got an eighty six hundred mile hike to Dallas and then in eighty-six hundred mile hike back. The amount of time that that takes is usually measured in milliseconds and just that round trip might be about a hundred and seventy milliseconds. For our users up in London that might be about a hundred milliseconds. Our users in New York City can probably experience about a forty milliseconds round-trip time. And over in LA about thirty. So, as you can see, the further you're away, the longer it takes and ultimately the slower the website will be for you. So, this is where the CDN comes into play and this is how it actually accomplishes the increase in speed which is by reducing the amount of distance between the user and the content, or the server providing the content. So, what it does by doing that it places these Content Delivery Network end points in as many locations around the world as possible. And in our case, we're going to assume we've got one in just about every location where users exist. So, now when the user in Sydney, or London, or New York City, or LA tries to access some content its first retrieved by the Content Delivery Network service and then distributed around the world. So, we have a single request down to the Dallas server. It's now the distributed all around the world. And our users in London now instead of going all the way to Dallas they're able to retrieve that content directly from their closest geographical location, drastically reducing the amount of time that it takes to retrieve that content. So, as you can see here it's a very basic how a CDN is able to provide the benefits of to the end user by reducing the amount of time that it takes to deliver the service, but what you're not seen here is an indirect benefit is the reduction in the amount of traffic that actually hits the Dallas server. So, the indirect benefit is that you actually see a reduction in the load, or the reduction in the amount of capacity that you need in Dallas to serve all these users. So, another indirect benefit because there is much less validity and so much less stuff happening in Dallas, because all these users are not having to make these trips, and I'm also not having to communicate with users so far away. The Dallas environment may also see an increase in up time. And then lastly because the users are not really directly communicating with the server down in Dallas you have the indirect benefit of an increase in security through obscurity. So, it's pretty basic to understand how a CDN works, in the end it provide a better benefit to the end user. Thanks for watching this overview of Content Delivery Network. If you liked it, or have any questions please comment below. Stay tuned for additional videos in the future and please don't forget to like and subscribe.