In satellite system redundancy, what characterizes hot standby?

• A. Hot standby keeps a redundant subsystem powered and ready to take over instantly.
• B. Hot standby powers down the redundant subsystem to save energy.
• C. Cold standby is always active and ready to replace a failed component.
• D. Redundant subsystems are never used during normal operation.

Answer: (A)

Hot standby means a redundant subsystem is kept powered and ready to take over instantly if the primary fails. This setup minimizes downtime because the handover is immediate and often automated, preserving continuous service on the satellite. If the spare is powered down to save energy, that describes cold standby, which introduces a delay when switching over. Warm standby sits in between, with the spare partially powered to reduce switch time. The idea that redundant subsystems are never used during normal operation isn’t a description of hot standby.