The Fallacies of
Distributed Systems
Design decisions made on false assumptions are the root of most system failures.
The 8 Fallacies
Originally coined by Peter Deutsch in 1994, these eight assumptions are still the hidden traps in modern cloud architecture.
1. The Network is Reliable
The Reality: Packets Drop
Switches fail, cables are cut, and congestion causes loss. You cannot assume your request will arrive.
Retries, Timeouts, and Idempotency keys.
2. Latency is Zero
The Reality: Light is Slow*
Even at the speed of light, a round trip across the globe takes ~200ms. In microservices, every hop adds up.
Caching, CDNs, and Batching requests.
3. Bandwidth is Infinite
The Reality: Congestion is Real
Moving massive JSON blobs or raw logs can saturate the network quickly, leading to slow responses for everyone.
Compression (Protobuf/gRPC) and filtering data at the source.
Interview Guidance
The "Skeptical Architect"
To show seniority in an interview, be a skeptic. When a plan depends on a synchronous network call, ask: "What happens when this times out?"
Mentioning Fallacies
Explicitly name-dropping the "Fallacies of Distributed Computing" shows you have a formal background in system design theory, not just ad-hoc experience.