--- title: "What Is a CDN? Content Delivery Network Explained" description: "A CDN is a network of servers that delivers video from a location near each viewer. See how it works, how it is priced and how to estimate your usage." url: "https://www.rentanott.com/glossary/cdn" markdown_url: "https://www.rentanott.com/glossary/cdn.md" category: "Streaming technology" updated: "2026-10-05" --- # What is a CDN? A CDN (content delivery network) is a network of servers spread across many locations that stores copies of content and delivers each request from a server near the viewer. For streaming, it is what carries the video segments from the platform to the audience. ## How a CDN works Your video lives on an origin server. When a viewer requests a segment, the request is routed to the nearest CDN location, called an edge. If the edge already holds that segment it sends it immediately; if not, it fetches it from the origin, sends it and keeps a copy for the next viewer. Popular content is therefore served almost entirely from the edge, close to viewers, without touching the origin. ## Why streaming needs a CDN - Speed: shorter distances mean faster starts and less buffering - Scale: thousands of edge servers absorb an audience no single origin could - Resilience: traffic is routed around failed or congested locations - Protection: the CDN shields the origin and can enforce signed URLs and geo rules ## How CDN usage is priced Delivery is billed by the volume of data transferred, per gigabyte or terabyte, often with lower rates at higher volumes and different rates per region. Rates vary widely between providers. Volume is viewing hours multiplied by average bitrate. As a rule of thumb, an hour at 5 Mbps is about 2.25 GB, so 100,000 viewing hours is about 225 TB at that bitrate, or 100 TB at an average nearer 2.2 Mbps. ## Reducing delivery cost - Tune the bitrate ladder so viewers are not sent more than their screens can show - Use a more efficient codec for your highest-volume content - Cap quality on mobile data by default - Compare the platform's included allowance and overage rate, not just its base price ## CDN on RentAnOTT RentAnOTT tiers include 1 TB, 5 TB or 20 TB of CDN delivery a month. Usage above the allowance is $0.0075 per GB, which is $7.50 per TB. [Estimate your delivery cost](https://www.rentanott.com/tools/streaming-bandwidth-cost-calculator). ## Related terms - [Multi-CDN](https://www.rentanott.com/glossary/multi-cdn) — Multi-CDN is the practice of delivering video through two or more content delivery networks at once, with a switching layer that sends each viewer, or each request, to whichever network is performing best for them at that moment. - [Bandwidth](https://www.rentanott.com/glossary/bandwidth) — Bandwidth is the maximum rate at which data can be transferred over a connection, measured in megabits per second (Mbps). In streaming the word is also used for the total volume of video delivered to viewers in a month, measured in gigabytes or terabytes. - [Egress cost](https://www.rentanott.com/glossary/egress-cost) — Egress cost is the charge for data leaving a cloud provider's or CDN's network, billed per gigabyte transferred. For a streaming service it is the cost of delivering video to viewers, and it is usually the largest variable cost of the service. - [Bitrate](https://www.rentanott.com/glossary/bitrate) — Bitrate is the amount of data used to represent one second of video or audio, measured in kilobits or megabits per second (kbps or Mbps). A higher bitrate carries more detail and produces larger files and higher delivery costs. - [Signed URL](https://www.rentanott.com/glossary/signed-url) — A signed URL is a web address for a video stream that includes a cryptographic signature and an expiry time. The CDN serves the content only if the signature is valid and the link has not expired, so a copied or shared link stops working. Using signed URLs for playback is called tokenized playback. - [Auto-scaling](https://www.rentanott.com/glossary/auto-scaling) — Auto-scaling is the automatic adjustment of computing capacity to match demand. When load rises, more servers are started; when it falls, they are shut down. For a streaming service it is what keeps sign-in, playback and payment working through an evening peak or a live event. - [Concurrent viewers](https://www.rentanott.com/glossary/concurrent-viewers) — Concurrent viewers is the number of people watching a service's video at the same moment. The highest value reached, peak concurrency, determines how much streaming capacity the service needs. ## Further reading - [Pricing](https://www.rentanott.com/pricing) - [Video bitrate calculator](https://www.rentanott.com/tools/video-bitrate-calculator) - [How to start a streaming service](https://www.rentanott.com/blogs/how-to-start-a-streaming-service) ## Frequently asked questions ### What does CDN stand for? CDN stands for content delivery network. ### Do I need to contract a CDN myself? Not on a managed platform, where delivery is included and billed as part of the plan. A self-hosted setup needs its own CDN contract. ### How much CDN traffic will my service use? Multiply expected viewing hours by your average bitrate in Mbps and by 0.45 to get gigabytes. The bandwidth cost calculator does this for you. All 163 terms: [Streaming and OTT glossary](https://www.rentanott.com/glossary). ## Book a demo Tell RentAnOTT what you are launching. The team walks through the platform and maps the path to go-live around your catalog, markets and revenue model. Book a demo: https://www.rentanott.com/contact ## More from RentAnOTT - [Home](https://www.rentanott.com/index.md) — What RentAnOTT is, what every plan includes, and how launch works - [Features](https://www.rentanott.com/features.md) — Every core feature and optional add-on - [Pricing](https://www.rentanott.com/pricing.md) — Platform tiers, apps, add-ons, usage rates and example bills in INR and USD - [Free tools](https://www.rentanott.com/tools.md) — OTT app builder and calculators for streaming revenue, bandwidth, bitrate and pricing - [Insights](https://www.rentanott.com/blogs.md) — All streaming business articles - [Glossary](https://www.rentanott.com/glossary.md) — Definitions of streaming and OTT terms - [Book a demo](https://www.rentanott.com/contact.md) — Talk to RentAnOTT about your launch Full site in one file: https://www.rentanott.com/llms-full.txt