Which of the following describes the four tiers of data center site infrastructure?

The correct answer identifies the four tiers of data center site infrastructure as Fault-Tolerant, Redundant, Basic, and Concurrently Maintainable, which reflects the widely accepted classification established by the Uptime Institute.

This classification system is crucial because it provides a standardized methodology for measuring the reliability and performance characteristics of data center environments.

• A Fault-Tolerant data center is designed to maintain operations even in the event of a failure, accommodating potential issues without causing downtime.

• The Redundant tier emphasizes having duplicate critical components that can take over if one fails, ensuring continuous availability.

• The Basic tier represents minimum levels of infrastructure required to support an operational data center but may not include advanced features for redundancy or fault tolerance.

• The Concurrently Maintainable tier allows for maintenance tasks to be performed without disrupting operations, meaning that it can tolerate multiple simultaneous equipment failures while still maintaining service availability.

Recognizing the correct order helps in understanding how advanced or resilient a data center infrastructure can be, which is essential for specific business needs and service level agreements (SLAs).