CDN (Content Delivery Network) is a distributed infrastructure of geographically separated servers designed to deliver content to end users from the nearest available location, reducing latency, improving load times, and increasing service reliability.
A CDN does not replace the origin infrastructure; it extends and protects it by offloading traffic and optimizing delivery paths.
What a CDN Does in Practice?
A CDN:
- Caches and serves content closer to end users
- Reduces latency caused by long-distance network paths
- Offloads bandwidth and processing from origin servers
- Absorbs traffic spikes and sudden load surges
- Improves availability during partial infrastructure failures
CDNs are especially effective for read-heavy workloads.
How CDN Works (Simplified Flow)?
- A user requests content (video, image, file, page).
- The request is routed to the nearest CDN node.
- If content is cached:
- It is served immediately.
- It is served immediately.
- If not cached:
- The CDN fetches it from the origin.
- Stores it according to caching rules.
- Serves it to the user.
Routing decisions are made using Anycast routing, DNS logic, and network proximity.
Types of CDN Content
CDNs are commonly used for:
- Static files (images, JS, CSS)
- Video streaming (live and on-demand)
- Software and file distribution
- API acceleration (in some cases)
- Game and application assets
Not all content benefits equally from CDN caching.
CDN vs Hosting vs Cloud
- Hosting runs applications and stores data.
- Cloud provides compute and storage resources.
- CDN focuses solely on content delivery optimization.
A CDN cannot fix slow backends or poorly designed applications; it optimizes delivery, not logic.
Key CDN Characteristics
1. Geographic Distribution
Nodes are placed in major internet exchange points and data centers close to end users.
2. Anycast Routing
The same IP address is announced from multiple locations, allowing traffic to flow to the nearest or best-performing node.
3. High Bandwidth Capacity
CDNs rely on wide channels and strong peering to handle large traffic volumes.
4. Caching Logic
Rules that define:
- What is cached
- For how long
- Under which conditions
Correct cache configuration is critical.
CDN and Reliability
A properly designed CDN:
- Reduces load on origin servers
- Provides partial service continuity if the origin is slow or unreachable
- Helps mitigate certain DDoS attack types
- Smooths traffic spikes caused by viral or seasonal demand
However, CDNs do not replace origin redundancy or backups.
Video CDN vs Static CDN
- Static CDN
- Files and assets
- Long cache lifetime
- High cache hit ratio
- Video CDN
- Large files, continuous streams
- High bandwidth consumption
- Requires specialized optimization for buffering and bitrate adaptation
Each requires a different architecture and tuning.
What CDN Is Not?
❌ Not a hosting service
❌ Not a replacement for servers
❌ Not a security solution by itself
❌ Not a “magic speed fix” for bad infrastructure
Business Value of CDN
For clients:
- Faster content delivery worldwide
- Reduced infrastructure load
- Improved user experience
- Lower origin bandwidth costs
- Higher resilience to traffic spikes
For us:
- A network-level extension of client infrastructure
- A performance multiplier for well-designed systems
Our Approach to CDN
We design CDN solutions based on:
- Client traffic patterns
- Content type (static, video, mixed)
- Geographic audience distribution
- Bandwidth requirements and growth plans
Our CDNs are built on dedicated infrastructure, high-capacity links, redirector layers and/or Anycast routing, ensuring performance is engineered, not assumed.