CAP theorem: a distributed system can provide at most two of Consistency, Availability, and Partition tolerance simultaneously.
2 / 5
During a network partition, what choice does CAP force?
Partition trade-off: because partitions are unavoidable in real networks, when one occurs the system must either reject requests (favor consistency) or serve possibly stale data (favor availability).
3 / 5
What characterizes a CP system?
CP: prioritizes consistency and partition tolerance; during a partition it may refuse reads/writes rather than return inconsistent results (e.g. systems using strict quorums).
4 / 5
What characterizes an AP system?
AP: favors availability and partition tolerance, continuing to serve requests during a partition while reconciling divergent state later.
5 / 5
What does the PACELC extension add to CAP?
PACELC: states that if Partitioned, choose Availability or Consistency; Else (normal operation) choose between Latency and Consistency, capturing the everyday tuning trade-off.