[ntp:questions] Re: What will happen if the only stratum1 (reference clock) is lost.

Richard B. Gilbert rgilbert88 at comcast.net
Wed Oct 6 14:27:54 UTC 2004

Ariel Burbaickij wrote:

>Hello dear mailing list participants,
>I have following question:
>Under the condition that the only  announced stratum1 server (server
>with attached
>reference clock) is lost in the network (physically detached from the
>what will happen to all other machines: Will they go in autonomous
>mode (local clock) or will they nevertheless try to get their time
>feed from announced stratum2 servers even if it is known that they do
>not get their feed from stratum1 server?
>With Best Regards
>Ariel Burbaickij
It depends on how the other machines are configured.

If your stratum on server with reference clock was the only server 
available and all machines use it, all of the local clocks will become 
unsynchronized and n different machines will have n different times.

For this reason, it is good practice to configure several external 
network servers as a backup and sanity check.  If time keeping is 
important in your application you should not rely on a single server or 
a single reference clock.

You might want to consider operating one or more stratum 2 servers.

Including the lines
# Declare the local clock to be the clock of last resort.
# It will be used to serve time in the absence of any other.
fudge stratum 10

in your stratum 2 server's ntp.conf would cause the stratum 2 server to 
continue serving time at stratum 10.
This will give you at least a few hours of "holdover".  You can't rely 
on it forever; that local clock will drift!

More information about the questions mailing list