Solving Time Sync Issue on Azure

We just came off an Azure project and we thought it would be useful to push out our notes on keeping a hosted server time in sync.

1. We were configuring a Linux hosted server on Azure and thehe NTP protocol uses UDP on port 123. But you don’t have to allow that on ‘iptables’ in Linux – NTP just gets passed through.

2. ¬†On Azure you don’t have to define the port in the VM configuration, like you do for 22/80/443.

3. Old) posts say Azure doesn’t support UDP, but it seems to now.

4. In theory, Azure provides a service “time.windows.com” but it was 80ms behind the standard servers at [0123].centos.pool.ntp.org.

After configuring the clock on the hosted Linux appliance starts drifting very quickly.
The problem seems to be that there are problems with the time sync in Hyper-V on Windows Server 2008, which is what Azure is built on.

The solution is to look at the changes required to grub.conf and ntp.conf as described at:

http://www.hardanswers.net/correct-clock-drift-in-centos-hyper-v

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