The NTP time services (RFC 1305) are a useful way to synchronize server clocks to a known good value. This service is so useful that MOVEit DMZ Resiliency sets up a NTP client as part of the installation. (MOVEit DMZ Resiliency services depend on accurate time on all nodes to help detect if other machines are "falling behind".)
Ipswitch recommends (and uses) a Windows utility called w32tm.exe ("Windows32Time") as an NTP client application on MOVEit DMZ servers. Detailed information about this client can be found by looking for w32tm documentation on Microsoft's site, but most time client configuration involves only one parameter (which server to use) and only one action (how to force a time synchronization now).
Time services are built Windows Server. Use the procedure below, from a command prompt, to configure them.
Execute the following command (where "ntp.yourisp.net" has been replaced with the hostname of a reliable time server such as "pool.ntp.org"):
C:\>net time /setsntp:ntp.yourisp.net
WARNING: If you use MOVEit DMZ Resiliency and wish to change a node's time server, you must ALSO change it in the "...siLock\Resil\DoNotReplicate\SNTPServer" registry key. See the Technical Reference for more information.
Execute the following command:
C:\>w32tm /resync /nowait Sending resync command to local computer... The command completed successfully.
MOVEit DMZ Resiliency has its own NTP client (not server), which is used in addition to the Windows time client. When in use, the MOVEit DMZ Resiliency client has the ability to directly set the time (often needed to avoid strange "sync" situations), whereas native Windows clients tend to speed up or slow down the clock to gradually push it back to a known value.
When running time clients on virtual servers (such as products from VMware or Microsoft's VirtualPC), it has been observed that the clock of the host operating system will usually be regarded as more authoritative than data from time clients running on the virtual servers. For example, if the host operating system says it is now 3:25 and a remote time server said it is 3:27, someone on the virtual OS console may see the time jump to 3:27 and then back to 3:25 in short order.
To minimize strange interactions like this, care should be take to keep the host operating system's time up to date and to avoid the use of time clients on virtual servers. Similarly, if MOVEit DMZ resiliency is run on virtual servers, the underlying host operating systems should both use the same time client and NTP host, and MOVEit DMZ itself should be configured to also point to the same NTP host.
A list of time servers available to the public is maintained at http://ntp.isc.org/bin/view/Servers/NTPPoolServers.
Bugs in the Windows Server 2003 time service prevent it from being a reliable time server. Therefore, avoid using a Windows Server 2003 host as a time source.