Consumer needs have changed in the past few years as far as content consumption is concerned. A lot of new technologies have emerged in order to optimize the user experience and improve the delivery of their content. On this line, one technology that is most talked about is the Content Delivery Network (CDN). It refers to an extensive globally distributed network of web servers that are used to deliver content faster to the audience. They are built with the purpose of delivering static content such as images, style sheets, documents, HTML, videos content, etc. In the modern fast-paced world, CDN has surely emerged out as a king and helped businesses in many ways such as increased client retention, faster public reach, decreasing load time for websites, and many more.

CDN has evolved over a long period of time and today businesses even have options to choose from different types of CDNs they want for their business. The top two options that businesses look at are- single CDN and Multi-CDN. Multi-CDN refers to the combination of multiple CDNs from different providers into a single network. The majority of application builders, especially those belonging to enterprise space tend to choose a multi-CDN strategy for the multiple benefits it offers.

The single-CDN architecture was initially the default model for all businesses where the website’s content is delivered by a single provider’s network. For a multi-CDN setup, web traffic is distributed with many CDNs. To put it in simple words, with a multi-CDN option the content is shared over multiple CDNs, your content is delivered across multiple networks, offering failover and redundancy. The number of CDNs in use when deploying a multi-CDN model varies depending on the application and its specific requirements. Because the quality of experience (QoE) is the most important factor of success along with heavy video sites, particularly those with live video streaming, they are required to have multiple CDNs in place.   

A single CDN has a limited capacity and individual PoPs or even CDNs can lead to failure on the other hand multi-CDN allows capacity from different utilities to combine and make them safe from fault tolerance in case a failure occurs. Multi-CDN setups have become more important than single CDN in today’s world because of growing conscience around brand reputation and thus their willingness to reduce the possibility of failure. Let’s look at the key factors which make Multi-CDN a better option over single CDN.

• The difference in CDN traffic
  This is the most obvious reason for brands to choose a multi-CDN In the case of a single CDN, whole traffic is diverted to just one point. The possibility of failure due to heavy traffic is really high. Whereas for multi-CDN, this is not the case as the total load is divided within multiple servers. The servers are very unlikely to fail together and thus the brands are very less likely to lose business in case of failure.
  
  
• Latency
  CDNs, which are based on HTTP architecture, are simply not designed to handle the transport of dynamically updated content, such as live videos. They function by caching data in regional data centers, enabling the efficient delivery of large amounts of data. The emphasis on throughput and scalability in this design results in a network that is best suited for handling static objects such as websites or pre-recorded videos. Caching affects latency which does not contribute much to static elements such as webpages or even VOD but live events are continuously interactive and latency is highly focused. Latency of just a second will poorly affect the end-user experience. With a single CDN the latency is very poor and is bound to hinder user experience. The case is different for Multi-CDN as the work is distributed and the work is done by multiple Points of Presence.
  
  

The list of pros about of having a multi-CDN setup is just endless. It has showcased way better performance than a single CDN did. It offers more flexibility to the clients as well as customers. The resilience level for multi CDN is also more favorable than the single CDN option.  Each new CDN adds new management interfaces and APIs, functionality, and administrative tasks. While a multi-CDN broker can abstract away some of the complexity, the underlying network topology is still more complex with multi-CDN.

A lot of people argue that single CDN is more economical but that’s not true. While single CDNs are set to be cheaper but multi-CDN offers better vendor management. along with cost control. The larger and more sensitive your application is to downtime and/or latency, the more likely the benefits of multi-CDN will outweigh the drawbacks. Similarly, once you’ve decided to use multi-CDN, the method of implementation is determined by the same criteria. Static DNS entries may be sufficient in some cases where some manual intervention is acceptable. A more variable-driven load balancing approach, on the other hand, maybe worth the upfront cost and complexity. 

When traffic spikes occur, such as on Black Friday or Cyber Monday, you can be confident that your applications will be able to scale to accommodate the unusual conditions by distributing traffic across multiple CDNs.In case you expect a major happening or a big live stream coming, the CDN service providers can plan and take appropriate steps.  If you anticipate a large live stream, for example, you can plan to distribute traffic across multiple CDN providers.

You can decide on key services and the best delivery model for the long term in terms of workload and budget by gaining greater control over your delivery expenditure. After meeting your pre-negotiated commitments with each provider, you may be able to shift traffic to providers with lower rates.

Multi-CDN service providers have an option to make changes according to change in network conditions by choosing the best delivery path. Having an option to choose different CDNs in diffrent geographical regions is a huge plus point. Thus we hope that this can help you make a better choice regarding the type of CDNs you want to go with.