[ntp:questions] Re: Yet Another Isolated Network Question

Richard B. Gilbert rgilbert88 at comcast.net
Fri Dec 17 01:41:42 UTC 2004

Bruce Baumgart wrote:

>I have been following the isolated network configuration discussions 
>because I am in a very similar situation.
>I need to sync our end of a widespread, but limited number of 
>connections, private network.  First, a few interjections of reality.
>1) It will remain completely, totally private.  No outside connections, 
>no matter how brief.  Never.
>2) I cannot simply add a GPS/WWVB/etc reciever.  End of discussion.
>3) I cannot alter connection methods, topology, etc.
>4) I am not interested in sub-second synchronization.  When I got brought 
>in, the DNS server and the SMTP server were 1/2 an hour apart, and had 
>been that way for a long time.  +/- a few seconds is fine <shudder>.
>There is one NTP server on the network.  
>My thoughts are to set up a local server, with a server statement 
>pointing to the remote server and one for my local clock.  I would advise 
>people to point their local machines to that one local server.
>If I lose my connection to the psuedo-outside world or that server, I 
>still want to be able to keep my local machines together, hence the local 
>clock thing.  The room is (mostly, usually) climate controlled, so what I 
>am hoping is that after the local server talks to the remote server for 
>awhile, it will have it's frequency adjusted and a proper value set in 
>the drift file.  That way, if my external link goes down, the local 
>server won't drift too far (hopefully) by the time things get restored.
>The clients are mostly, if not completely, Windows-flavored things.  I 
>have to assume that they would sync to me by SNTP.  I have no visibility 
>to them.
>Will NTP work the way I think it will in these circumstances?  Mainly 
>thinking about the local server serving time, not drifting too far, etc?
It should work to the extent that everybody on your local network should 
be within a second or so of the server 

The server will drift and everybody should follow it.  If you want a 
reasonable approximation of the correct time someone will have to adjust 
your server's clock periodically.

It's rather like using a limousine to haul garbage but what can you do?

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