Answer Description

Out-of-band management is the use of a trusted, dedicated management channel for accessing a network device. This data is transmitted separately from in-band data such as network traffic.

Wikipedia

In systems management, out-of-band management (OOB; also lights-out management or LOM) is a process for accessing and managing devices and infrastructure at remote locations through a separate management plane from the production network. OOB allows a system administrator to monitor and manage servers and other network-attached equipment by remote control regardless of whether the machine is powered on or whether an OS is installed or functional. It is contrasted to in-band management which requires the managed systems to be powered on and available over their operating system's networking facilities. OOB can use dedicated management interfaces, serial ports, or cellular 4G and 5G networks for connectivity. Out-of-band management is now considered an essential network component to ensure business continuity and many manufacturers have it as a product offering.