Saturday 1 February 2020

Demystifying Content Delivery Networks/ CDNs

The idea of a CDN is to bring media rich content geographically closer to the people viewing the content and in turn, provide an optimal experience for the people consuming that content. A CDN improves download speeds, reduces buffering and improves application performance by shortening the distance between the users and the servers hosting the content. The beauty of a CDN from the content provider’s perspective is the ability to have that content distributed all around the world while only having to upload that data to one “origin server”. Once the content is uploaded to the origin server, the CDN distributes that content across each of the points-of-presence or “POPs” within minutes.


Something called POPs:


A CDN consists of multiple points-of-presence or “POPs” scattered across the globe. Each of these POPs is located at different points on the globe. Each POP location is chosen with the singular goal of creating a network that will provide the best performance to as much of the world as possible. At that point, anyone requesting the content will receive the content from the POP that is closest to their physical location. For example, people in Los Angeles will pull content from the US West POPs and people in London will pull content from the EU POP or other closer ones to their locations. This proximity logic works around the globe ensuring an optimal experience for every end-user.

Why use CDN:

CDNs are a great way to speed up the loading times and reduce latency/ round-time delays by caching your data.

Content Delivery Network also provides security from various attacks like SQL injection and denial of service (DOS) and keeps your website safe.

CDN also automatically does Load Balancing during high traffic times and your website speed is not affected.

POP- What Exactly is in it:

It is a system consisting of a number of servers distributed around the globe. Each Point of Presence then contains multiple caching servers. These servers are what actually do the hard work of caching all of your site’s static files. All these servers contain cached static content of your website. Whenever a user visits your website, the server nearest to the user, (which is based on the geographical location of the user), will provide him your website’s static content. The static content of a website includes – CSS files, JavaScript and Images. The content sometimes need not be static. For example, Netflix will cache its entire content library to speed up the buffering of videos.

BILLING IN CDNs:

So how exactly does a CDN billing work? As you know, with a dedicated server you are typically provided with a lump sum of monthly bandwidth (ex. 10TB or 100TB) on a certain sized port (ex. 100Mbps or 1Gbps). So long as you do not exceed the amount of bandwidth included each month, you just pay the base rate for your server. A CDN works differently. With a CDN you pay per GB of outbound data transfer right out of the gate and there is no port size limitation. In most CDNs, as the amount of data you transfer each month grows, your price per GB goes down. So, it makes sense for bigger companies to go for CDNs- either build it themselves if you are Netflix or so for providers like Akamai or Cloudflare if you are reasonably big and want better performance.


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