Which data center tier is characterized by fault-tolerant infrastructure?

The tier that is characterized by fault-tolerant infrastructure is Tier IV. This classification under the Uptime Institute's tier system defines a data center that ensures high availability and reliability. Tier IV data centers are designed with fully redundant components and multiple active paths for power and cooling, which helps prevent any single point of failure from impacting operations. This architecture allows for constant availability, even during maintenance or unexpected issues, ensuring that the infrastructure can continuously support critical operations without outages. Overall, Tier IV represents the highest level of reliability in data center design.