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The Time Synchronization Hierarchy
        The NTP daemon can not only adjust its own computer’s system time.        Additionally, each daemon can be a client, server, or peer for        other NTP daemons:

  •         As client it queries the reference time from one        or more servers.
  •         As server it makes its own time available as        reference time for other clients.
  •         As peer it compares its system time to other peers        until all the peers finally agree about the “true” time        to synchchronize to.

These features can be used to set up a hierarchical time        synchronization structure.        The hierarchical levels of the time synchronization structure        are called stratum levels. A smaller stratum        number means a higher level in the hierarchy structure.        On top of the hierarchy there is the daemon which has the most        accurate time and therefore the smallest stratumnumber.

By default, a daemon’s stratum level is always one level        below the level of its reference time source.        The top level daemon often uses a radio clock as reference        time source. By default, radio clocks have a stratum number        of 0, so a daemon who uses that radio clock as reference time will        be a stratum 1 time server, which has the highest        priority level in the NTP hierarchy.        In large networks it is a good practice to install one ore more        stratum 1 time servers which make a reference time available        to several server computers in each department.        Thus the servers in the departments become stratum 2 time servers        which can be used as reference time source for workstations and        other network devices of the department.

Unlike in telecom applications where the word stratum is used        e.g. to classify oscillators according to their absolute accuracy,        the term stratum in the NTP context does not indicate a certain        class of accuracy, it’s just an indicator of the hierarchy level.


1.Sync the time with ntp, login as root, type
#ntpdate ntp_ip_address

2.Edit file /etc/ntp.conf and add
server ntp_ip_address
driftfile /etc/ntp.drift
tracefile /etc/ntp.trace


more /etc/ntp.conf

server time_server01 prefer
server time_server02
driftfile /etc/ntp.drift
tracefile /etc/ntp.trace
3.smitty xntpd
select BOTH

  1. Let the daemon run for about 10 mins then type:

lssrc –ls xntpd

Program name:    /usr/sbin/xntpd
Version:         3
Leap indicator:  00 (No leap second today.)
Sys peer:        time_server01
Sys stratum:     2
Sys precision:   -18
Debug/Tracing:   DISABLED
Root distance:   0.000458
Root dispersion: 10.166382
Reference ID:
Reference time:  d3b125c4.78c4d000  Wed, Jul 18 2012 15:08:36.471
Broadcast delay: 0.003906 (sec)
Auth delay:      0.000122 (sec)
System flags:    bclient pll monitor filegen
System uptime:   1102 (sec)
Clock stability: 1358.841064 (sec)
Clock frequency: -16.000000 (sec)
Peer: time_server02
flags: (configured)(sys peer)
stratum:  2, version: 3
our mode: client, his mode: server
Peer: time_server01
flags: (configured)(sys peer)(preferred)
stratum:  1, version: 3
our mode: client, his mode: server
Subsystem         Group            PID          Status
xntpd            tcpip            12283954     active