What Is a Content Delivery Network (CDN)

When it comes to loading websites constructed with HTML, CSS, JavaScript, and other assets quickly, many options exist. A Content Delivery Network (CDN) is one of these ways. CDN is a group of servers that gives all types of online content a boost to speed. The overall goal is to improve website load time so people can enjoy the Internet more fully and without delay.

CDN

Instead of relying on the host to handle everything, the content delivery network loads certain elements of the site from a server that is geographically closer to the end user.

Besides speeding up load times, a CDN and can also help websites enjoy a more reliable service. They may even increase security by doubling up on various measures that the web host may or may not already provide. This is especially important on large sites that may be the target of a DDOS attack.

Because Content Delivery Network servers exist all around the world, the communication between a website or service and a user’s machine experiences a lot less latency. After all, the data or code does not have to fly all the way around the world to get to an individual computer. This also helps improve uptime by giving a particular website more points of distribution than the server uses by the hosting company.

Websites that attract high levels of international traffic need this service in order to make content delivery quicker. A CDN uses geo-specific servers within a network to deliver web pages more quickly than without. It copies the site, caches the content, and delivers it to the end user more conveniently when they load it up. Instead of getting the assets directly from the originating server, it retrieves them from the nearby location server. CDNs minimize load waits, bandwidth usage, boosts security and availability of global websites to all users.

Advantages:

  • Reduced load on the web server so it can focus on other things
  • Generally, cookie-less and session-less, which speeds up transfers
  • Usually configured for pure speed (advanced compression, http2)
  • For common assets like Google fonts/JS libraries – may already be cached in browser
  • Some CDNs optimize/auto-size images before they are served

Disadvantages:

  • Additional browser connections due to the different domain
  • Might have longer network latency if the CDN doesn’t have a POP in the target country