In ESX (not ESXi) there were two clocks, the hardware clock (CMOS clock, BIOS clock) and the system clock ("linux kernel" clock). The hardware clock could be synchronised manually to the time of the system clock by using "/sbin/hwclock --systohc" and as far as i know (correct me if i'm wrong) if NTP on the ESX host was configured properly the NTP server took care of syncing the hardware clock to the system clock on a more or less regular basis.
Now, my questions: Does this concept also apply to ESXi? Does the NTP server inside ESXi sync the two clocks? If yes, how often? If not, is there only one clock? I cannot find any up to date information on this topic in the VMware documentation, everything points to ESX (not ESXi).