Final answer:
A cluster placement group is used in cloud computing for instance placement and can only be used within a single Availability Zone to optimize for low latency and high throughput.
Step-by-step explanation:
A cluster placement group is a concept used in cloud computing to dictate how instances are placed within a cloud infrastructure. When we refer to an AZ in the context of a cluster placement group, we're talking about an Availability Zone. Availability Zones are distinct locations within a cloud region that are engineered to be isolated from failures in other AZs.
In the context of Amazon Web Services (AWS), a cluster placement group can only be used within a single AZ. This means that all the instances that are part of a cluster placement group will be located within the same Availability Zone to achieve the lowest latency and the highest throughput. It's important for users to carefully plan the deployment of a cluster placement group to ensure they meet their performance and high-availability requirements.