This value, carried in NTP-related notifications, names the VPN instance associated with the NTP peer the local clock was previously synchronized to, before the source change. Admins use it together with hwNtpOldSource to fully identify the prior time source, including which VRF it was reached through, when auditing an NTP failover event. For example, seeing this change from "MGMT-VRF" to a different VPN name alongside a source-address change would show the device's NTP path moved to a different VRF entirely.