Providing users with great, engaging content is no longer enough to build a robust video streaming service and win loyal users. In an increasingly crowded streaming market, a fast and seamless viewing experience is gaining importance as a key distinguishing factor helping your OTT platform get ahead of the competition. 

In video streaming, timely delivery of content is the foundation of a great user experience. A Content Delivery Network is a piece of technology which ensures the fast distribution of video content across the globe, constituting the backbone upon which all modern over-the-top platforms operate. 

What is a CDN?

A CDN is a piece of technology which consists of a network of servers located in different places around the world. These proxy servers can store various content such as images, audio and video files. Usually, when a user opens a streaming platform and tries to access a piece of content, the file is served not from the origin server but from the proxy server closest to their location.

Most websites and streaming platforms use CDNs to some extent, but the technology is particularly important for resource-intensive content. Because video and audio streaming platforms are more vulnerable to slow loading speeds and buffering delays, they must use speedy CDNs.

What functions do CDNs serve for OTT platforms

In layman terms, using a CDN reduces latency and buffering time, and improves the overall viewing experience. Without a CDN, all your content would have to be served from the master/origin server located in a geographically distant location. No matter how powerful, your server will sooner or later bend under a growing number of requests from your user base, and won’t be able to serve the content quickly to distant locations across the globe. This could negatively affect the user experience. 

 Due to diversified demands of video content consumption and distribution, today’s CDNs must serve many different functions apart from just storing and feeding high-quality video content to end-user devices. Let’s briefly discuss these functions.

Increased buffering and streaming speed 

The buffer provided by the CDN is critical for the good performance of an OTT streaming service, ensuring that your OTT platform can take unexpected surges in traffic while protecting the master server from excessive load. 

In spite of the user’s fast internet connection, one (or both) of the following can happen:

  • Instead of starting immediately, the player will take a long time to buffer the video before playback finally starts. This happens because the server isn’t able to ensure the streaming speed needed by the device. In extreme cases the video doesn’t start at all – there are too many concurrent requests to the origin server to serve the content.
  • The video player will automatically switch to lower video quality to adjust to the low bitrate from the origin server.

From a user experience point of view, either of the above issues can be a recipe for disaster. Integrating a CDN will help you avoid such problems.

When a piece of content is cached on the edge (a server located in a geographically close location) a user logging into the streaming platform will be able to quickly resume video playback by accessing the file from the CDN without sending a request to the master server. 

Streaming-specific features

Certain CDNs, like Cloudflare, provide support for adaptive bitrate streaming, sophisticated security measures like digital rights management (DRM), and multi-protocol delivery varies across providers. It’s important to consider such features when looking for a CDN provider and comparing them side by side.

Reduced hosting bills

Huge streaming overlords build their own global network of servers to provide content worldwide, but this route may not be the most economical for most content distributors. CDNs allow broadcasters to outsource infrastructure and maintenance costs without losing global reach. This is possible due to the function of CDNs called caching.

Caching allows CDNs to reduce hosting bandwidth and thus reduce the risk of service interruptions or diminished quality – is now essential to many broadcasters as they seek to satisfy the phenomenal appetite for new and different content. 

Better OTT Performance and uptime

Using CDNs helps to decrease load on the origin server, and decreases time to serve high bitrate video chunks. 

The distributed network of proxy servers also ensures a consistently high uptime ratio for your OTT platform. This means that even if the main server is temporarily down, the viewers won’t experience any delays or gaps in streaming media. Combined with the reinforced security features, a CDN ensures that your video service is available round-the-clock.


Somewhat connected to the point above, CDNs play a critical role in preventing DDoS attacks. This is done by setting up rules on the edge to drop requests from certain clients or IP addresses reaching the origin servers. CDNs can thus act as the shield protecting the source of the content and ensuring the origin servers are not blocked by too many incoming requests. In the event of a DDoS attack, proxy servers are the only ones likely to get affected. The bigger the number of proxy servers, the lower the risk of an effective DDoS attack.


Specific highly-anticipated live events are connected with sudden spikes in viewership. Investing in a highly-performant origin server can help you handle these spikes, but it’s an intrinsically costly and inefficient solution to the problem.

  • No matter how fast, the master/origin servers are usually located in close proximity.
  • Because outside the peaks you usually don’t usually need such a high bandwidth, investment in origin infrastructure may simply not be viable from the cost perspective.

A CDN gives you the benefit of scalability, providing additional resources (add-on proxy servers) when you need them. In this way, the infrastructure will scale back immediately when the peak time is over, saving you unnecessary cost. 

How does a CDN work with a video streaming platform?

The video content is typically stored on the origin server and served using the HLS or DASH protocol (more on that in another article on our blog). The CDN knows the location of the video files, but does not cache the file until it’s first requested by the OTT player.

When an OTT player asks the CDN for a video which is not yet cached on the CDN server in a closer geographical location (i.e. it’s a cache miss, more on that later), it goes directly to the origin server. The CDN then receives the response from the origin server, caches the content and sends it to the player.

The next time the video player or another video player in the same geographical proximity requests the same video segment, the CDN has it and serves that video from its cache (cache hit).

Of course, the CDNs store the segments only for a limited time, which is referred to as TTL (time to live, more on that below)

Cache miss, cache hit and TTL

When talking about CDN, it’s important to understand some key concepts like cache miss, cache hit and time to live (TTL).

Cache Miss

A cache-miss means a client requests content which is not (yet) stored on the CDN. When a cache miss occurs, the CDN needs to send a request back to the origin server and retrieve that missing content. The origin server then responds, and the CDN receives the content and caches it for future use (i.e. at least for some time, see the term TTL below) and immediately serves it to the client.

Cache hit

A cache hit means that a client requested a piece of content which is stored on the CDN. The CDN immediately serves the content.

Time to Live (TTL)

It would be physically impossible for a CDN to store the contents of the master/origin server 1:1 in every geographical location at the same time, indefinitely. This is why CDNs use a variable called Time to Live (TTL) to define when to discard or flush the cache, deleting the infrequently requested content. In this way, the CDN intelligently makes space for newer, more frequently requested content.

Does your platform really need a CDN?

As discussed in the paragraphs above, CDNs provide many benefits for video streaming platforms. However, chances are you don’t even need to use one. This might the case in one of the following scenarios:

  • You have a small number of viewers. Your platform is niche and the source/origin server can handle all the requests until you grow big. 
  • You don’t distribute content to international audiences. If your viewers are located in the same country, chances are you will be fine serving the content from a single local hosting server.
  • You are running on a really tight budget. Our team will help you decide if the investment in a CDN is likely to bring a reasonable return. It’s also important to know that there are both paid and free CDN options available, so you don’t need to shell out from the get-go.

Integrate your OTT with a Content Delivery Network

Using a CDN enhances your OTT platform’s security, reliability, and scalability. It ensures that users don’t experience buffering delays or downtime. Perhaps indirectly, a CDN thus contributes to better viewing experience and reduces subscriber churn.

If you’re looking to integrate your OTT with a CDN or are interested in the possible benefits of doing that, send us an email. Our team of experts will be happy to discuss your project.