What does CAP actually mean?
Understand the concept
CAP describes a limit on distributed systems during a network partition. If nodes cannot communicate, the system cannot guarantee both a single up-to-date view of data and a successful response to every request to non-failing nodes. It must sometimes sacrifice availability or allow responses that may not satisfy that consistency guarantee.
Important ideas
-
During a network partition, a system cannot guarantee both linearizable consistency and availability for every request.
-
It must sometimes reject/delay requests or allow responses that may not reflect the latest write.
-
It is not a general rule to “pick any two” for all normal operation.
-
Partition tolerance is not a switch that prevents network failure; the design must decide what happens when communication breaks.
Can you explain it without the notes?
What does CAP actually mean?
Use your own words. Explain an example and one limitation before checking the explanation.
Check your explanation
CAP describes a limit on distributed systems during a network partition. If nodes cannot communicate, the system cannot guarantee both a single up-to-date view of data and a successful response to every request to non-failing nodes. It must sometimes sacrifice availability or allow responses that may not satisfy that consistency guarantee.
Turn this concept into a clear answer.
- Use a two-node example and state what each side does when it cannot confirm the latest write.
Adapted from 07_SYSTEM_DESIGN_ARCHITECTURE.md · “What does CAP actually mean?”. Examples are study fragments; framework behavior can depend on your version.