1. We cannot recover the alarm by product documentation.
AD/DNS serer ping NTP server, network is normal, restart the 'Windows Time service' in AD/DNS server, the alarm still cannot recover.
2. Login AD/DNS server and run 'win32 /query /status', AD/DNS server don't configure clock source as below.
3. Login FusionAccess -> system -> Time Management, FusionAccess don't configure upper-layer clock source as below.
4. Configure upper-layer clock source and save configuration in FusionAccess, after several minutes the alarm automatically clear.