The management option that can provide on-site infrastructure access when the network is down or complete remote access in cases of connectivity failures on the network, such as via a cellular signal, is known as?

It is known as out-of-band management

Explanation:

Out-of-band management is a device and system management technique that involves an alternative and efficient connection to the system which is separate from the main network that the system runs on allowing an administrator to establish a system of trust boundaries since there would only be a single entry point for the management interface.

Device management through out-of-band management is very secure and safe because it does not allow any unauthorized user to be able to access the network channel because there is no connection from the regular network channel that is available for everyone.

This channel management interface is very efficient and a very powerful management tool because it is always available even when network is down or device is turned off or not accessible through the operating system making it easy to be remotely managed.

An example configuration for out-of-band management is the blade systems with dedicated management modules often offering a dedicated OOB Ethernet port

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