What else needs to be checked in a more complex infrastructure (hundreds of servers, dozens of domain controllers)?

In an infrastructure with hundreds of servers and dozens of domain controllers, it is necessary to check not only basic availability and operability, but also:

• The correctness of replication and synchronization between domain controllers.
• Security settings and Group Policy (GPO) configurations to ensure they are correctly applied on all nodes.
• Performance monitoring and load on servers to identify bottlenecks.
• Security event logs and system logs to detect anomalies.
• Network connectivity and routing between servers.
• Data backup and recovery.
• Updates and patches to keep all nodes up to date.

It is also important to automate monitoring and alerts to quickly respond to failures or violations in the infrastructure's operation.