This read-write INTEGER specifies the priority tier of a configured clock source: primary(1), secondary(2), tertiary(3), or null(4). An administrator configures which timing sources serve as the primary reference versus backups, so the node has a defined failover order for network synchronization. For example, setting one clock entry to primary(1) and another to secondary(2) ensures the node automatically falls back to the secondary source if the primary clock fails.