Re: Sync Date & Time via NTP?

["Lukas Beeler" <lukas.beeler@xxxxxxxxxxxxxxxx>]

On Thu, Dec 18, 2008 at 21:18, Jeff Crosby <jlcrosby@xxxxxxxxxxxxxxxx> wrote:
> My System I syncs itself to timesrvr1.external.com and every PC in here
> syncs itself to the System i.

Be aware that relying on a single external (essentially untrusted)
timesource may not always be the best idea.

Essentially, bigger companies should not rely on an external
timesource. It may make sense to purchase a hardware devices that has
it's own precision clock and can also sync to GPS.

e.G http://www.symmetricom.com/products/ntp-servers/ntp-network-appliances/SyncServer-S200/

(Random Google Result for NTP Appliance)

For smaller companies, consistency is key: Designate a stratum 1
server, and sync everything else against it. I would advise against
using the i for this, as it's NTP implementation is rather limited
(not full NTP, just SNTP). This makes for a poor stratum 2 server.

Best choice: A unix-y machine with ntpd - e.G. an AIX or Linux LPAR,
or an x86 Linux server if you have one.

Second best choice: A properly configured Windows Server
(http://support.microsoft.com/kb/816042)

If you are using Active Directory, the PDC FSMO Role Holder will also
be the primary timeserver for all other DCs, and the clients will
automatically sync against their nearest DC (using AD Sites). So in
such configurations, it makes sense to sync your i against the PDC
FSMO Role Holder. This is what i'm doing.

There are lots of other devices that need to sync time - printers,
routers, access points, firewalls, etc. pp. Setting the proper DHCP
attributes will automatically configure all appliances that are
configured using DHCP (e.G. printers, access points, etc.).

Centralized Logging with proper timestamps is the next step in lin,
but this would stray to far from the original topic. But proper
timekeeping is key in a well-managed network.