Which class of data center is characterized by two separate infrastructures with their own redundant components?

The correct answer focuses on the definition of data center classes as outlined by the Uptime Institute's Tier Classification System. Class 4 data centers are specifically designed to handle critical applications with a high level of availability and reliability. What distinguishes Class 4 is that it comprises two separate infrastructures that operate independently yet simultaneously, providing full redundancy for every component, including power, cooling, networking, and storage.

This level of resilience is crucial for organizations that cannot afford any downtime, making Class 4 suitable for mission-critical environments. Both of the infrastructures can function without the other, ensuring that maintenance or failure in one system does not disrupt operations in the other. This design allows for continuous operation even during catastrophic events or maintenance periods.

In contrast, lower classes like Class 1, Class 2, and Class 3 do not provide the same level of redundancy or fault tolerance as Class 4 does, making them less suitable for environments with the highest demands for consistent availability.