"ID",Meaning Source,Reference
ACST,The association belongs to a unicast server,[RFC5905]
AUTH,Server authentication failed,[RFC5905]
AUTO,Autokey sequence failed,[RFC5905]
BCST,The association belongs to a broadcast server,[RFC5905]
CRYP,Cryptographic authentication or identification failed,[RFC5905]
DENY,Access denied by remote server,[RFC5905]
DROP,Lost peer in symmetric mode,[RFC5905]
RSTR,Access denied due to local policy,[RFC5905]
INIT,The association has not yet synchronized for the first time,[RFC5905]
MCST,The association belongs to a dynamically discovered server,[RFC5905]
NKEY,No key found. Either the key was never installed or is not trusted,[RFC5905]
NTSN,Network Time Security (NTS) negative-acknowledgment (NAK),"[RFC8915, Section 5.7]"
RATE,Rate exceeded. The server has temporarily denied access because the client exceeded the rate threshold,[RFC5905]
RMOT,Alteration of association from a remote host running ntpdc.,[RFC5905]
STEP,"A step change in system time has occurred, but the association has not yet resynchronized",[RFC5905]