[ntp:questions] NTP and NAT

Richard B. Gilbert rgilbert88 at comcast.net
Thu Nov 8 14:23:07 UTC 2007

Daniel Guerrero wrote:
> Hello,
> I'm a newbie on NTP, and i would like to know if there is any problem in
> configuring more than one machine with the same NTP server on a LAN that
> connects to the internet through a NAT (with the same outgoing IP for
> everyone).

I've done it. It works.

Normally, you should not have more than one local client per outside 
server.  If you need to synch several machines, make one the master that 
synchs to the outside server(s) and have the rest synch to your internal 
server.  Many of the stratum one and two servers are staggering under 
the load caused by misconfigured clients, see; e.g. 
and that is by no means the only example.  Some of the others can be 
found by googling for "Poul Henning Kamp D-Link" and "Tardis NTP". 
Remember: more than 40% of the population has subnormal intelligence. :-)

If you are setting up a configuration that requires maximum robustness, 
you would use four internal servers synchronized from a set of seven or 
more external servers.  Each internal server would use a different set 
of external servers.  Not everyone needs this level of robustness!

More information about the questions mailing list