# CDN / Edge Caching

> A mechanism that serves cacheable content from servers near the requester, keyed by a fingerprint of the content.

Record: `architecture:cdn-edge-caching`
Kind: mechanism
Layer: [Performance Core](https://banes-lab.com/records/layer/performance-core.md)
Severity: contextual
Scope: service, infrastructure, latency
Aliases: Content Delivery Network
Canonical: https://banes-lab.com/ontology#architecture-cdn-edge-caching

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Memory Efficiency](https://banes-lab.com/records/architecture/memory-efficiency.md) and before [Read Replica](https://banes-lab.com/records/architecture/read-replica.md).

## Repair

- Refactored by: Serve via CDN / Edge Cache
- Detected by: static assets served from origin per request
- Violated by: every request hitting the origin regardless of locality
- Measured by: origin request rate / cache hit ratio
- Enforced by: performance review

## Requires

- [Cacheable Content](https://banes-lab.com/records/lexicon/cacheable-content.md)

## Reinforces

- [Caching](https://banes-lab.com/records/architecture/caching.md)
- [Latency](https://banes-lab.com/records/architecture/latency.md)

## Enables

- [Origin Offload](https://banes-lab.com/records/lexicon/origin-offload.md)
- [Geographically-Local Delivery](https://banes-lab.com/records/lexicon/geographically-local-delivery.md)

## Conflicts with

- [Origin-Only Serving](https://banes-lab.com/records/lexicon/origin-only-serving.md)

## In tension with

- [Cache Invalidation](https://banes-lab.com/records/lexicon/cache-invalidation.md)

## Tensions

- [CDN / Edge Caching / Cache Invalidation](https://banes-lab.com/records/tension/cache-invalidation-cdn-edge-caching.md)

## Severity

- [contextual](https://banes-lab.com/records/vocabulary/severity-contextual.md)

## Category

- [Scalability / Performance / Optimization](https://banes-lab.com/records/architecture-category/scalability-performance-optimization.md)

## Linked from

- [Scalability / Performance / Optimization](https://banes-lab.com/ontology/principles/architecture-category-scalability-performance-optimization.md)
- [Scalability / Performance / Optimization](https://banes-lab.com/ontology/lexicon/lexicon-category-scalability-performance-optimization.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)