I have a ESXi host running ~20 virtual machines (mostly EL6, but also one or two Windows Server 2008 R2).
What is the best practice for timekeeping on virtual machines?
I'm thinking about 3 different ways to do it, but I'm having trouble to find pros or cons on the internet for such methods.
1) ESXi syncs with 0.pool.ntp.org and then sets the BIOS time on each VM
2) Each guest OS syncs with 0.pool.ntp.org
3) Each guest OS syncs with ntp.localdomain (a VM on my ESXi server acting as a cached proxy to 0.pool.ntp.org)
I think the third option would be the better one since it reduces outgoing network traffic from my WAN interface, and it provides a precise time between all VMs.
Could you tell me if there is a better alternative?