[ntp:questions] NTP not synchronizing to server

Richard B. Gilbert rgilbert88 at comcast.net
Sun Jan 7 02:18:26 UTC 2007


george_joby wrote:

> Richard B. Gilbert wrote:
> 
>>george_joby wrote:
>>
>>
>>>Hi
>>>
>>>I am trying to configure NTP for Redhat Linux AS 4 update 4 running in
>>>DL585 with Windows Server 2003.
>>>My ntp is no longer synchronizing with the servers specified in
>>>ntp.conf
>>>
>>>Client: Redhat Linux ntp.conf
>>>
>>>server 172.16.0.201 prefer
>>>
>>
>><big snip>
>>
>>The server address you mention is on an RFC-1918 private network and
>>presumably it's your local network or you wouldn't be able to reach it
>>at all!  It is serving its local clock.  It is claiming stratum one
>>which is a very dangerous thing to do.  Please, please, NEVER connect
>>this mess to the internet; somebody might believe that stratum 1!
>>
>>If you MUST serve your local clock, "fudge" it to stratum 10 like this:
>>#
>># Declare the local clock to be the clock of last resort.
>># It will be used to serve time in the absence of any other.
>>#
>>server 127.127.1.0              # Local clock, unit 0
>>fudge 127.127.1.0 stratum 10
you is that what you are doing will never work!
<snip>
> 
> 
> ===========================================
> 
> Hi
> 
> Yes I am connected to a server using cross cable and in our requirement
> we didnt want to connect to any external server thru the internet.
> 
> Client (172.16.0.200) and Server (172.16.0.201)
> 
> [root at txnaslload03 ~]# ping 172.16.0.201
> PING 172.16.0.201 (172.16.0.201) 56(84) bytes of data.
> 64 bytes from 172.16.0.201: icmp_seq=0 ttl=128 time=1.48 ms
> 64 bytes from 172.16.0.201: icmp_seq=1 ttl=128 time=0.106 ms
> 64 bytes from 172.16.0.201: icmp_seq=2 ttl=128 time=0.137 ms
> 
> I will check the orphan mode .... But I would like to know whether
> there is any issue in synchronzing with a Windows server running
> win32time.

The issue with W32TIME is that it is an SNTP implementation.  It is 
designed to keep a flock of PCs synchronized to within +/- 2 minutes 
which is necessary in order for Kerberos authentication to work.  No 
SNTP system should EVER act as a server unless it is connected to a 
hardware reference clock!  SNTP simply does not have the "industrial 
strength" features that allow NTP (when correctly used) to guarantee the 
correct time .

You can get your NTP subnet working in a supported fashion by installing 
a "hardware reference clock".  The cheapest is a Garmin GPS18LVC which 
sells for about $85 US.  Connecting one of these to your server and 
configuring it properly will make your server a true stratum 1 server 
which should keep time with an accuracy +/- a few microseconds.  With 
such an ultra stable/ultra accurate time source, your whole network 
should be able to synch up within a millisecond or two.  Depending on 
the hardware and software you are running you might even get 
synchronization in the low microsecond ranges.




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