Microsoft Azure Architect Design (AZ-304) Practice Test

The most appropriate storage tier for data in Azure Blob storage that will be accessed rarely but must remain immediately available is the Cool tier. The Cool tier is specifically designed for data that is infrequently accessed but needs to be readily available when needed. This tier balances cost and accessibility, making it suitable for scenarios where the data may not be accessed frequently but cannot have the latency associated with archive solutions.

The Cool tier has a lower storage cost compared to the Hot tier, which is intended for data that is accessed frequently. Meanwhile, it supports immediate access to the data, unlike the Archive tier, which is optimized for long-term storage of data that is seldom accessed and may require retrieval time. Premium storage is geared towards workloads that require high performance and low latency, typically associated with high transaction levels or intensive I/O operations.

In summary, the Cool tier provides an economical solution while ensuring that data is quickly accessible when needed, making it the ideal choice for the specified requirements in the question.