xntp

[HP-UX Enthusiast]

Hi All
I have setup a NTP server (node1), below is the entries in /etc/ntp.conf on this server:

broadcast 106.10.1.255 version 3
fudge 127.127.1.1 stratum 10
server 127.127.1.1

Below are the entries in the NTP clients:

server node1 version 3 prefer

The clients do remain in sync with the NTP server, and that is not the issue. My problem is that when I change the time on the NTP server the clients take at least, and in some cases a lot longer, than 25 minutes to make the time reset to come back into sync with the NTP server. Some servers simply state they lose synchronisation with the server (message in syslog.log) and never regain sync.

Does anyone know how I can make this reset quicker? Immediate would be best, but as close to that will do - at any rate it should be a lot quicker than 25 minutes.

Many thanks.

[Steven E. Protter]

Shalom,

Yes, you can get the TIME Zone TZ settings conistent throughout the shop.

What is happening is the time zone is switching on the time server but not the clients. Therefore it takes time for the ntp clients to adjust the the change in the time server.

This is normal as ntp clients run their internal clocks slower or faster than normal in order to sync with the server.

If TZ is consistent on all servers, the switch will be instantaneous and transparent through all servers.

SEP

[Bill Hassell · Accepted solution]

NTP is designed to keep time in sync but also sane. An NTP server is assumed to be accurate and therefore, there will never be a time jump more than a second or two. If you change time, perhaps 20 minutes ahead or behind, then NTP clinets will rightfully reject the sanity of the time server and do nothing. The most important task in NTP is to ensure that every second in the day (all 86400 of them) will occur. Databases can become unstable or corrupted if time jumps around. This is alos the reason that multiple time servers are a must for accuracy.

If the server is changed by about 10 minutes, you can expect the resync time to be about 3 hours. xntpd adjusts time by slowing or speeding up the clock very slightly. Clients will never jump to a new time, nor do you want this to happen. If it is necessary to change the time a large amount, you must reboot every client. Or you can stop all time-sensitive applications, then manually stop xntpd, set the time in the client and then restart xntpd.

[Antonio Cardoso_1]

Hi,

have a look at xntpd man page, which contains much interssting information on how NTP works.
When manually setting the time on your NTP server, you should run a ntpdate command on clients connected to that server.

In addition, your NTP server could be synchronize on an external time reference.