CentOS 7 ntpd not synchronize with AD domain controller

centos7ntpd

i've a problem with time syncronization of a CentOS 7 host with a Windows 2008 R2 Domain controller.
If I use the command ntpdate -u host.domain
the synchronization is ok.
But using ntpd the time is always the same, here the result of the command ntpq -p:

 10.10.10.221    .LOCL.           1 u   65   64  377    1.740  965414.   4.054
 10.10.10.220    10.10.10.221     2 u   62   64  377    1.912  965408.  12.899

and the ntp.conf is the following:

driftfile /var/lib/ntp/drift
restrict default nomodify notrap nopeer noquery
restrict 127.0.0.1
restrict ::1
server 10.10.10.221 iburst prefer
server 10.10.10.220 iburst
includefile /etc/ntp/crypto/pw
keys /etc/ntp/keys
disable monitor
logfile /var/log/ntp.log

Best Answer

I managed to find the solution after digging in more to a very similar issue on my end (different OS but same problem).

Windows NTP Servers (at times for various reaons), will report a large root dispersion. This in turn causes chronyd/ntpd to ignore the ntp server fpr inaccurate data.

In order to resolve I needed to add:

tos maxdist 16

to my /etc/ntp.conf. After restarting the service everything began working.

This article helped gave a simple explanation.

https://access.redhat.com/solutions/4652771

I also stumbled upon this post regarding inadequate times which further helped troubleshoot and identify the issue.

Why is NTP considering my server inadequate?

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