[ntp:questions] how to have offset < 1ms

lhommedumatch ludocluba at yahoo.com
Mon Apr 12 20:04:59 UTC 2010


I have my PC clock synchronised with a ntp server (ntpgmtaceb).

With ntpq -p, I see an offset of 6ms.
How can I be sure to have an offset < 1ms

ntpq -p
     remote           refid      st t when poll reach   delay
offset  jitter
==============================================================================
 LOCAL(0)        .LOCL.          10 l   61   64  377    0.000
0.000   0.001
*ntpgmtaceb      .1PPS.           1 u  709 1024  377   29.431
-6.450   0.917

Here is my ntp.conf:
# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default kod nomodify notrap nopeer noquery

# Permit all access over the loopback interface.  This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1
restrict -6 ::1

# Hosts on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/
join.html).

#broadcast 192.168.1.255 key 42         # broadcast server
#broadcastclient                        # broadcast client
#broadcast 224.0.1.1 key 42             # multicast server
#multicastclient 224.0.1.1              # multicast client
#manycastserver 239.255.254.254         # manycast server
#manycastclient 239.255.254.254 key 42  # manycast client

# Undisciplined Local Clock. This is a fake driver intended for backup
# and when no outside source of synchronized time is available.
server 127.127.1.0
fudge   127.127.1.0 stratum 10

# Drift file.  Put this in a directory which the daemon can write to.
# No symbolic links allowed, either, since the daemon updates the file
# by creating a temporary in the same directory and then rename()'ing
# it to the file.
driftfile /var/lib/ntp/drift

# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography.
keys /etc/ntp/keys

# Specify the key identifiers which are trusted.
#trustedkey 4 8 42

# Specify the key identifier to use with the ntpdc utility.
#requestkey 8

# Specify the key identifier to use with the ntpq utility.
#controlkey 8
server ntpgmtaceb
restrict ntpgmtaceb mask 255.255.255.255 nomodify notrap noquery

Regards,
Ludovic




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