A content delivery network, also known as a CDN, is a system that uses distributed servers in order to deliver relevant content to users.
The distribution of websites and web pages is done based on the geographic location of both the end user and the accessed web page.
Using a CDN quickens the delivery of content to end users.
These networks are especially useful for websites which have a global reach. Moreover, CDNs can also protect websites against traffic surges by redirecting users to the closest server.
Whenever a user tries to access a website, the nearest CDN server to their geographical location receives the request and responds. The content of each website that uses a CDN is copied and cached within hundreds of servers that are dispersed across the globe.
Once a request is made to access one of the webpages, the CDN redirects the request to the appropriate server, which then delivers the cached content to the end user. The continuous data exchange between the originating server and the CDN allows for the servers to receive any new content that hasn’t already been cached.
How Exactly Does a CDN Work?
A lot people don’t really understand how CDNs work, but they still use them. However, the process through which CDNs make website requests faster is quite simple to understand.
Whenever an end user makes a request for a web page, the web browser makes a DNS (Domain Name System) request. This allows the web browser to receive the IP address of the requested website. Once the browser acquires the IP address, it can directly access the data provided by the web server. Moreover, once the IP address of the website is acquired, the browser can directly inquire the web server for any following requests made by the user.
A downside of internet communication is the fact that data must travel a certain distance between the user and the servers. When we attempting to access a server located in Australia, from a computer located in Europe that data will take longer to travel than it would take to access a server located in Europe from the same computer.
This is where CDNs come into play.
The server which handles the DNS request will direct the request towards the CDN server that is physically closest to the end user. These CDN servers, which are also known as edge servers, act like a proxy cache. Whenever the server receives a request, it checks for an already existing cache.
Once it determines that the cache is present and still valid, it delivers the content to the end user. However, if the cache has expired, or the content requested is simply unavailable in the current cache, the CDN server requests a new cache from the main website server.
What Are the Benefits of Using a CDN?
Overall, there are very limited downsides to buying a CDN. However, rarely is it considered a mandatory purchase. If you’re running a local website, a CDN will not provide you with any real benefits. But, if your website has a good amount of international traffic, then it (and its visitors) will greatly benefit from a CDN.
The cost of implementing a CDN varies from provider to provider, but when put in balance with the benefits, it doesn’t usually cause a financial problem. In the end, a CDN will reduce the load times of your website for users from around the globe, especially if you have a lot of media files - such as images, videos, and so on.
Therefore knowing your audience, being clear on objectives and monitoring results is a great starting place to determine whether a CDN is a good choice for you.