CDNs appear in CloudNetX scenarios as performance and resilience tools, and this episode explains how to decide when a CDN is appropriate and where it belongs in the delivery path. It defines a CDN as a distributed edge layer that caches and serves content closer to users, reducing latency and reducing load on the origin service. The first paragraph focuses on the core concept of cacheability: static assets and predictable responses benefit most, while highly dynamic or personalized content requires careful controls. It also explains why a CDN can improve availability by absorbing spikes, smoothing bursts, and providing distributed capacity that reduces the chance that origin infrastructure becomes the bottleneck. Placement matters because a CDN changes how users reach services, how TLS is terminated, and how caching rules impact correctness and user experience.