What is a Multi CDN?

Multi CDN is a strategy of using more than one CDN (Content Delivery Network) provider in order to further improve latency, uptimes and cost efficiency on a global scale.

With Multi CDN, website content is distributed and delivered across multiple CDN providers. With each CDN provider’s availability, website latency is further reduced for more users in various geographic regions.

multi cdn

Having a Multi CDN setup in place also helps improve redundancy as if one CDN provider’s network goes offline, the content will continue to be delivered from the alternative providers.

Delivery over a multiple CDN architecture is a best practice for modern Ops teams. Ensuring uptime and multiple delivery contingencies give teams peace of mind and the ability to reduce the adverse effects of vendor lock-in. When you’re able to load balance your application, video, and website content delivery across multiple CDN, you can ensure your end users are shielded from service degradations and outages.

Different CDNs tend to vary in performance in different areas, and some may offer a better service in video optimization, for example. Choosing a Multi CDN strategy is a fairly new practice that’s becoming more common as businesses have become more familiar with the technology.

Multi CDN Features

  • CDNs are selected based on what will be fastest for the individual user. If there are multiple providers in one region, the content will be served from the fastest one.
  • If a CDN providers network goes down, traffic will be routed through another provider. This means Multi CDN can guarantee a 100% service uptime.
  • Access to a huge amount of CDN locations, which wouldn’t have been possible with one provider.
  • CDN data centers can handle many more requests than a single server. This helps to relieve the load on your main server.

How does Multi CDN work?

There are many ways to manage and operate them depending on situations and scenarios. The following are some of the common methods used for a Multi CDN scenario:

  • Round robin – Dynamically divides CDNs equally during the process and makes sure all CDNs are put into work in turns. Round robin is easy to implement in general, but it doesn’t take extra factors into accounts, such as geographical location or other network conditions.
  • Weighted round robin – AKA Ratio Load Balancing, allows users to prioritize each CDN for traffic distribution. For example, you can set the traffic distribution load for CDN A to 90% and CDN B to 10%, so the system will distribute traffic to these CDNs accordingly to its settings.
  • Geolocation – Traffic is distributed between CDNs based on user’s location. This will dynamically activate CDNs based on where traffic originates. Location can be defined down to the country, state or city level. mlytics AI Load Balancing feature enables users to optimize at city-level for China and state-level for the US.
  • Performance – Takes current network conditions into account to meet optimal website performance. This approach involves measuring network conditions and make decisions based on the data collected. mlytics AI Load Balancing feature uses RUM (real user monitoring) to collect real user data to achieve performance-based Multi CDN load balancing.
performance-based multi cdn
How the performance-based Multi CDN works

The platform will assign the optimal path (CDN) for users around the world, and avoid CDNs that might take longer to access or are currently broken.

Multi vs Single

While one CDN may be enough in a certain locality, a site owner may choose to implement further CDNs that have data centers in geographical areas where the main supplier isn’t highly represented. 

Multi CDN is highly preferred over single CDN because:

  • CDN providers perform differently in different geographical regions
  • Not all CDN providers are reliable as others
  • Not all CDN providers include the same features and strategies as others
  • You don’t need to switch CDN providers as this process becomes automated
  • It’s the next big thing in e-commerce

One reason businesses choose Multi CDNs is so they don’t have to put all their eggs in one basket. While one supplier might offer 100% uptime, choosing more than one supplier means having a fallback should any supplier suffer an outage.

Does Multi CDN mean multi CNAME records?

The answer is no.

Multi CDN possesses multiple content delivery network providers, each provider will have different CNAME requirements. Most often CDN providers will insist on maintaining your DNS.

Next article:
Why do you need Multi CDN »