On 5/9/2011 1:31 AM, Per Jessen wrote:
Stan Hoeppner wrote:
This is not correct. You're assuming that ntpd doesn't perform sanity
checks on the system time when the daemon starts, which is not the
case.
The sanity check may be disabled with -g in which case using
ntpdate/sntp/ntpd -q at start up becomes pointless.
'ntpdate -q' has always been 'pointless', unless you just want to look
at the offset without modifying the clock. I do so on occasion to see
how accurately my local ntp server is keeping time. For instance:
/$ ntpdate -q tick.wustl.edu ntp.okstate.edu tick.uh.edu
server 128.252.19.1, stratum 1, offset -0.003486, delay 0.09729
server 139.78.135.14, stratum 1, offset 0.003479, delay 0.11545
server 129.7.1.66, stratum 1, offset -0.003950, delay 0.13434
9 May 02:39:55 ntpdate[31040]: adjust time server 128.252.19.1 offset
-0.003486 sec
Mt nptd server is Debian Squeeze atop kernel 2.6.34.1, running ntp
4.2.6.p2+dfsg-1+b1. The machine is home grown w/ an 11 year old Abit
main board. 0.003 seconds offset, not too shabby. ;) I've seen offset
with 4 leading zeros (after the decimal) in the past. I've never seen
less than two leading zeros. For most applications on my network, time
this accurate is overkill, but it's nice to have.
I acquired 'special' permission many years ago to use a few stratum 1
USNO servers mostly because at that time I lived in a city where one of
them is located, and because I only have one client querying
infrequently. USNO is the official time keeper for the US Military and
the US Government, including ships at sea via GPS. USNO has the most
accurate timekeeping devices on the planet--atomic clocks. Most (if not
all) of the stratum 2 servers in the US query the USNO stratum 1 servers.
--
Stan
