Doubts about NTP Server

Posted on 2006-11-16
Medium Priority
Last Modified: 2013-12-27
Hello Experts,

I want my Solaris/Linux server to have correct time always. How can I do it using NTP?

Suppose if I want my server to have the correct PST time always, how can I do that? Do I need to synchronize my server to any Time server?

NTPQ result of a server is shown below. What this tells?

ntpq> peers
     remote           refid      st t when poll reach   delay   offset    disp
 NTP.MCAST.NET         16 -    -   64    0     0.00    0.000 16000.0
*tick.ucla.edu   .PSC.            1 u  245  512  377    19.23   -1.241    1.33
-ntp-nasa.arc.na .GPS.            1 u  354 1024  377     8.12   -2.358    0.50
+time.nist.gov   .ACTS.           1 u  269  512  376    41.24    0.807    3.56
-time-a.nist.gov .ACTS.           1 u  942 1024  377    79.03   -6.712   25.88
-tick.usnogps.na .USNO.           1 u  697 1024  377   119.96   27.760    1.82
-egr-dns-1.egr.u nist1.symmetric  2 u   33 1024  377    44.54    5.119    8.00
+louie.udel.edu  NAVOBS1.MIT.EDU  2 u  231  512  377    82.35   -1.123    1.48
ntpq> quit
> xntpdc

Question by:rdashokraj
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LVL 48

Expert Comment

ID: 17961076
You already have NTP setup and working correctly, so what's the problem?

Author Comment

ID: 17961168
Tintin,  I don't have much idea about how NTP works. The Setup what is shown in my result is done by someone.

Could you please give me a brief idea about how to setup a NTP Server assuming that it needs to have a correct PST time?

Then in the above given result, which server is acting as the NTP Server? I used 'ntpq' command by looking at some stuff in the Net.


Author Comment

ID: 17961180
I'm leaving for the day now, will check your response approx. after 8 hours. Thanks.
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LVL 48

Accepted Solution

Tintin earned 1200 total points
ID: 17961319
Firstly, NTP keeps the system time in sync.  This has nothing to do with timezones like PST, which are just an offset from UTC.

In the ntpq output, it shows your NTP configuration uses multicast address (NTP.MCAST.NET) to obtain a list of various NTP servers.  You should always reference at least 2 NTP servers if possible in case one of the NTP servers is unavailable or gets totally screwed for some reason.  NTP uses come complex calculations when using multiple sources to ensure the most accurate time.

The st column, refers to stratum.  The lower the number, the higher the accuracy.  The stratum 1 servers on the Internet that are provided by NASA and similar places use atomic clocks or Satellite to obtain the time, so they are very, very accurate.

The other columns refer to various stuff like the offset of your local clock from the NTP servers.

man ntpq

for more details.
LVL 38

Assisted Solution

yuzh earned 800 total points
ID: 17961950
>>Tintin,  I don't have much idea about how NTP works. The Setup what is shown in my result is done by someone.

Please have a look at the NTP FAQ and How To:

and the following Sun NTP docs:

Author Comment

ID: 17965904
Tintin, Thanks for your explanation. Feel like I got the concept but need to learn more about it.

Yuzh, Wonderful documents !! Thanks so much.

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