juniorCAP Theorem
Explain Availability in the context of CAP.
Updated Apr 28, 2026
Short answer
Every request receives a (non-error) response, without the guarantee that it contains the most recent write.
Deep explanation
The CAP Theorem is a fundamental principle in distributed systems design. Every request receives a (non-error) response, without the guarantee that it contains the most recent write. It forces architects to acknowledge that trade-offs are unavoidable in wide-area networks.
Real-world example
A single-node relational database behaves as CA until it scales horizontally.
Common mistakes
- Thinking CAP applies to systems that aren't distributed (like a single-instance DB).
Follow-up questions
- Is CAP relevant for single-core apps?