What Is a CDN?

Here are some key terms you should know when it comes to CDN infrastructure:

This is the technology CDNs are built on. Deployed in front of your backend server on the edge of your network, a reverse proxy is a server that acts as a middleman between a website user’s device (also referred to as client) and the website’s origin server.

The reverse proxy intercepts the user’s request, such as when a webpage is loading in a browser. It prevents the user’s server from communicating directly with the origin server. In a CDN, the reverse proxy communicates with the origin server for the client, and will send the client’s request to the server which is closest to them geographically.

Short for Internet Exchange Point, an IXP is the physical location a network (such as a CDN) connects with.

A Point of Presence is a geographic location where a group of CDN edge servers is stored. When you use a CDN, users will be directed to the closest PoP to them.

This is where the copies of your website content are cached. As the name suggests, an edge server exists on the ‘edge’ of a network, acting as a point of entry between two networks. They are placed in IXPs, so that different networks can connect quickly and securely. When cached content from your site is successfully delivered to users from the edge server, this is known as a cache hit. Whereas a missed cache hit refers to when content is pulled from the origin server.

There are a host of benefits to using a CDN. Here are the top three:

As explained, CDNs will cache your website’s data on servers in interconnected locations around the globe, which allows for a short distance between users and where website assets are stored. This shortened distance results in high-speed data delivery, a fast website.

Additionally, because your website’s data is distributed across several servers, your website is more likely to have uninterrupted service and less downtime. If there is a rapid boost in traffic or a server failure, traffic will be redistributed to other servers.

Many CDNs have built-in protection from DDoS (Distributed Denial-of-Service) attacks. A DDoS attack is an attempt by malicious actors to interrupt service of your website by flooding a targeted server or network with more Internet traffic than it can handle, which can render a website unavailable. A CDN helps to block these kinds of threats from ever reaching the origin server by redistributing traffic to other servers.

Most CDNs also integrate SSL Certificates, which means that all traffic is encrypted (data is rendered unreadable to unauthorized parties).

CDNs take the pressure off origin servers when it comes to delivering assets. As a result, they lower hosting bandwidth consumption. This lowers hosting costs – which can be a big expense for websites.