Dell N20 Serie Guía De Introducción página 21

Stacking Standby
The stacking feature supports a Standby or backup unit that assumes the
Master unit role if the Master unit in the stack fails. As soon as a Master
failure is detected in the stack, the Standby unit initializes the control plane
and enables all other stack units with the current configuration. The Standby
unit maintains a synchronized copy of the running configuration for the
stack. The Standby unit is automatically selected in the stack; however, you
can use the CLI to select a different stack member as Standby. See the User's
Configuration Guide or the CLI Reference Guide for more information.
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Getting Started Guide