In regular environments, UNAB is configured to restart in case of failure. So, if uxauthd goes down, it will restart itself automatically. However, there may be cases when either the agent of one endpoint or several endpoints is unable to restart.
Why does the UNAB agent not restart automatically when there is a communications problem ?
CA PIM 12.8.X and CA PAM SC 14.X
Communications with the message queue should not prevent UNAB from starting up, but if that coincided with Active Directorty or DNS access issues, then UNAB would fail to start. If the site you are connecting to has only one Domain Controller server that goes offline (or zero online KDC in the site) when UNAB is restarting, it will fail to start. It is recommended to have several Domain Controllers per site configured in UNAB if possible.