CAP Theorem and Its Applicability to SQL Databases

Question: Explain the CAP theorem, and discuss whether it applies to traditional SQL (relational) databases.

Answer outline: CAP theorem states a distributed data store can only guarantee 2 of 3 properties at once: Consistency (every read gets the latest write), Availability (every request gets a response), and Partition Tolerance (the system keeps working despite network partitions). It applies to distributed SQL setups (e.g. a replicated/sharded Postgres cluster) — a single-node relational database isn't "distributed" in the CAP sense, but as soon as you replicate or shard it across nodes, the same C-vs-A tradeoff under partition applies, just as it does to NoSQL systems.