Five configurable levels in Azure Cosmos DB that trade off consistency against performance: Strong, Bounded Staleness, Session (the default), Consistent Prefix, and Eventual, ordered from most to least consistent and from lowest to highest availability/throughput.
AZ-305 asks which level to choose for a given scenario: Session is the most common default (it guarantees a client always sees its own writes). Strong gives full consistency but higher latency and lower multi-region availability.
Cosmos DB consistency levels is a concept that can show up on the exam. Check the full guide to see it in context.