Start with the idea
When the network splits you either refuse writes to stay consistent, or accept them and diverge. Everything else — quorums, leader election, eventual consistency, CRDTs — is a way of choosing where on that line to sit. Saying pick two is the answer that gets followed up; saying what your system does during a partition is the one that lands.
The CAP result is about what a distributed system can guarantee when a network partition separates participants. If it keeps accepting operations on both sides, it cannot also guarantee a single immediately consistent view of those operations. If it preserves a strong consistency contract, some requests may have to wait or fail until communication is restored. This is a narrower and more useful statement than treating consistency, availability, and partition tolerance as three features you choose on a normal day.
Describe a two-region account service during a partition.
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