Catalog
concept#Platform#Architecture#Reliability

Content Delivery Network (CDN)

A CDN distributes content via a global network of edge servers to reduce latency and improve availability for web, video and API traffic.

A content delivery network (CDN) distributes static and dynamic content across a global network of edge servers to reduce latency and improve availability.
Established
Medium

Classification

  • Medium
  • Technical
  • Architectural
  • Intermediate

Technical context

DNS providers (e.g. Route53, Cloud DNS)Cloud storage or origin serversMonitoring and logging tools

Principles & goals

Edge‑first: cache content close to users.Consistency management: define clear invalidation and TTL rules.Security: integrate TLS, WAF and DDoS protection.
Run
Enterprise, Domain, Team

Use cases & scenarios

Compromises

  • Misconfigured caches can serve stale content.
  • Dependency on third parties can increase outage risk.
  • Security issues at edge points can expand attack surface.
  • Define clear cache rules and TTLs for different content types.
  • Enforce TLS and security headers at the edge.
  • Integrate automated invalidation strategies into deployment pipelines.

I/O & resources

  • Assets to deliver (static/dynamic content)
  • DNS access and domains
  • TLS certificates and security configuration
  • Edge-cached assets at PoPs
  • Reduced origin load and bandwidth usage
  • Monitoring data for latency and cache performance

Description

A content delivery network (CDN) distributes static and dynamic content across a global network of edge servers to reduce latency and improve availability. It accelerates delivery, offloads origin servers and provides load balancing plus geo-based optimizations. Use cases include websites, video streaming and API acceleration.

✔

  • Lower latency via regional edge locations.
  • Improved scalability during traffic spikes.
  • Reduced origin load and bandwidth costs.

✖

  • Not all content is easily cacheable (personalized, dynamic).
  • Geographical coverage depends on the provider.
  • Invalidation can become complex and costly.

  • Time to First Byte (TTFB)

    Time until first byte from edge/origin – indicator of latency.

  • Cache hit ratio

    Share of requests served from the edge cache.

  • Origin bandwidth consumption

    Bandwidth consumed by the origin server; shows CDN offload effect.

Use in an international e‑commerce platform

Global product images and static content are delivered via a CDN to reduce load times and avoid checkout outages during traffic spikes.

On‑demand video streaming platform

Video files and manifests are hosted at edge servers; adaptive bitrate and regional PoPs improve quality and availability.

API gateway with edge caching

Read-heavy API endpoints use edge caches to reduce response times globally and lower origin load.

1

Analyze content and classify by cacheability

2

Select CDN provider based on PoP coverage and requirements

3

Configure DNS routing, TLS setup and cache policies

4

Test with load tests and validate cache hit rates

5

Set up monitoring and define invalidation/update processes

⚠️ Technical debt & bottlenecks

  • Legacy cache rules not aligned with new content.
  • Manual invalidation scripts instead of integrated CI/CD pipelines.
  • Missing monitoring for cache hit rates and latency changes.
Origin server performanceNetwork bandwidth between PoPs and originCache invalidation processes
  • Delivering personalized user pages via CDN without proper cache-control.
  • Setting TTLs indefinitely and serving stale data.
  • Serving sensitive data (PII) unencrypted through public edge caches.
  • Unclear invalidation leads to hard-to-find errors.
  • Misunderstandings about cache hierarchies between provider and origin.
  • Excessive complexity due to differing provider features.
Network and CDN architecture knowledgeConfiguration of caching, TTL and invalidationMonitoring and performance analysis
Minimize latency for global usersScalability during traffic spikesImprove availability and fault tolerance
  • • Legal constraints for geo-targeting and data sovereignty
  • • Non-cacheable dynamic content limits benefits
  • • Dependency on provider PoP locations