Bug ID 862001: Improperly configured NTP server can result in an undisciplined clock stanza

Last Modified: Apr 20, 2022

Bug Tracker

Affected Product:  See more info
BIG-IP All(all modules)

Known Affected Versions:
12.1.0, 12.1.0 HF1, 12.1.0 HF2, 12.1.1, 12.1.1 HF1, 12.1.1 HF2, 12.1.2, 12.1.2 HF1, 12.1.2 HF2, 12.1.3,,,,,,,, 12.1.4,, 12.1.5,,,, 12.1.6, 13.0.0, 13.0.0 HF1, 13.0.0 HF2, 13.0.0 HF3, 13.0.1, 13.1.0,,,,,,,,, 13.1.1,,,,, 13.1.3,,,,,,, 13.1.4,, 13.1.5, 14.0.0,,,,,, 14.0.1,, 14.1.0,,,,,, 14.1.2,,,,,,,,, 14.1.3,, 14.1.4,,,,,,, 15.0.0, 15.0.1,,,,, 15.1.0,,,,,, 15.1.1, 15.1.2,, 15.1.3,, 15.1.4,, 15.1.5,, 16.0.0,, 16.0.1,,

Opened: Dec 13, 2019
Severity: 3-Major


There can be an undisciplined clock stanza in /etc/ntp.conf, resulting in an undisciplined clock. NTP documentation: http://support.ntp.org/bin/view/Support/UndisciplinedLocalClock


When the LOCAL undisciplined clock is left as a valid time-source, it delays the system synchronizing time to a real NTP server. It can also result in time being adjusted incorrectly if the the remote time-source becomes unreachable.


This might occur in at least the following ways: -- No server is specified in 'sys ntp servers {}'. -- A server does exist, but an improper method was used to configure the NTP server.


Configure a dummy server via 'ntp servers {}' that does not respond. While this removes the undisciplined local clock, it does result in ntpd having an unreachable time source, and could be flagged in diagnostics, misdirect other troubleshooting, generate unnecessary traffic, etc. However, if the 'dummy' source starts responding, it could become a rogue time source.

Fix Information


Behavior Change