When visiting an extremely fast-loading website, you may have this question in mind: “does this website use a CDN?“. “If yes, which CDN provider it is using?“.
In this post, I will show you how to find out whether or not a website uses a CDN and which CDN provider it uses if it does.
CDN itself is a must-have feature for websites that serve visitors globally. It can help to speed up your website by reducing round-trip times and network latency.
Using CDN can also save the bandwidth usage of your origin server since data is not always retrieved from the origin server.
Shortcuts:
- Understanding how a website works
- Origin server vs CDN servers
- Finding out the CDN provider a site is using
- Summary
Understanding How a Website Works
The very first thing you need to do before you can find out whether or not a website uses CDN is to understand how a website works.
When you are accessing a website using a web browser, there are two activities involved: request and response.
The request is made by a client (your web browser) and the response is made by a server where the website is hosted. The two parties (client and server) communicate via an internet protocol called HTTP.
From this process, you can learn that the request made by a client is called HTTP request and the response made by the server is called HTTP response.
In a standard configuration, only one server handles all HTTP requests.
For a small website with a small number of visitors, this standard configuration is enough. A different story goes for websites with a huge number of visitors.
Let alone a website with global users/visitors. This is where CDN comes into play.
A CDN can help to reduce the work of the origin server by serving the requests made by users/clients.
How a CDN Works
As said above, only one server handles the HTTP requests in a standard server configuration (a configuration without CDN).
The more requests made (meaning more website visitors), the longer it takes for the server to respond. If the requests are too many and the server is no longer able to handle them, then an error message shows up.
With a CDN, the chance of the server to be unable to handle the requests is extremely low because it now has partners — the CDN servers — to handle the requests.
CDN itself works by storing static website files like HTML pages, JavaScript files, CSS files, images, and videos on the servers on its network. These files are generated by the origin server during the initial request made by users.
The next time visitors from the same location make the same request, the closest CDN server will serve the request.
Origin Server vs CDN Servers
Origin server is the server where a website is hosted. It contains some applications, including a web server, which plays a role to handle the requests made by users before it forwards the requests to CDN servers.
Some examples of popular web server applications are:
- Apache
- Nginx
- LiteSpeed
CDN servers, meanwhile, refer to the distributed servers in the CDN network.
Each CDN provider has a different number of servers on its network. Cloudflare, for instance, has over 330 server locations around the world.
NOC.org, the CDN provider used by Rapyd Cloud, has over 20 server locations worldwide.
Popular CDN Providers
There are tons of CDN providers available on the internet. Having a list of them on your mind can make it easy for you to find out which CDN provider a site is using.
Here are some examples of popular CDN providers:
- Cloudflare
- Fastly
- NOC.org
- Amazon CloudFront
- Akamai
- BunnyCDN
- QUIC.cloud
Finding Out the CDN Provider a Site is Using
When you are accessing a website, you are (the user) making a request to the origin server. The server will then forward the request to CDN servers to check whether the static files associated with the request are already available.
If the static files are already available on one of the CDN servers, then the CDN server will serve the request. Not the origin server.
But how to know if your request is served by the origin server or CDN server?
First, visit the website you want to check and open Developer Tools. You can find it under the More Tools menu in both Google Chrome and Firefox.
Alternatively, you can also open Developer Tools by right-clicking anywhere on the website you want to check and select Inspect.
Once the Developers Tools window opens, go to the Network tab and reload the website. This will display a list of all the requests. You can click the main URL of the website you want to check.
A new window will show up after you click one of the requests. Open the Response Headers block under the Headers tab on the window and take a look at the Server line.
From the Server line, you can learn whether your request is served by the origin server or CDN server.
If it says something like “Apache“, “Nginx“, or “LiteSpeed“, this means that your request is served by the origin server.
Conversely, if it says something like “cloudflare“, “noc.org“, etc (you can see the list above), this means your request is served by a CDN server.
An extra note. If you really want to know whether or not a website uses a CDN, you can use a VPN service like ExpressVPN or NordVPN and set the VPN location to the US. That’s because most CDN providers have server locations in the US.
If you access a website from a region where the CDN server is not available, your request will be served by the origin server. Using a VPN can help in this situation.
Summary
If you run a website that serves visitors globally, then CDN is a feature you need to add. CDN can help to improve the performance of your website by reducing the work of the origin server.
If you want to use the same CDN provider used by a certain website (because its performance impresses you), you can use the above method to find out which CDN provider the site is using.
You don’t need an extra tool to find out the CDN provider a website is using. You just need to understand how a website works. Your web browser has a built-in feature you can utilize to answer your curiosity.
