For remote monitoring and control of a server farm using KVM, which condition is necessary?

For remote monitoring and control of a server farm using KVM (Keyboard, Video, Mouse), the condition that the host must be reachable via the IP address is essential. This is because KVM over IP allows administrators to manage servers remotely from anywhere in the world, as long as there is network connectivity. When servers are configured for remote access, they must have a valid IP address that can be accessed through the network.

This capability enables the KVM switch to communicate with the servers, allowing the administrator to monitor and control them without needing physical access. Without the ability to reach the servers via IP addresses, remote management and monitoring become impossible, as there would be no way to send commands or receive feedback from the server.

Other options do not provide the necessary conditions for KVM operation. For instance, remote control being disabled would hinder management capabilities, while needing a serial cable is not relevant to KVM over IP functionality. Similarly, having a monitor attached to every server is not a requirement for using KVM switches, especially when remote access is the focus.