This read-only DateAndTime value indicates the last time a Multi-Chassis Link Aggregation Group (MC-LAG) was switched over between chassis. Admins use it to determine how recently a failover occurred and to correlate it with other event logs or outage reports during troubleshooting. For example, an admin investigating a brief traffic disruption would check whether this timestamp aligns with the reported incident window to confirm an MC-LAG switchover was the cause.