[ntp:questions] what is refid in ntpq -pn

Hans Mayer hans.mayer.08 at gmail.com
Sat May 6 21:24:42 UTC 2017



Dear All, 

I always thought "refid"  for command "ntpq -pn" shows the next upstream server for the remote server listed below "remote". But now I have my concerns. 

Lets explain my situation: 
I have 4 application server. Lets call them a1 till a4. And I have 4 internal ntp server ntp1 till ntp4. These are stratum 2 server. All of them ( appl and ntp ) are running  ntp version 4.2.8p10
Each application server has 4 server config lines and 2 peer config lines in ntp.conf. 
The 4 lines with server are my 4 ntp server ntp1 till ntp4 and the peer lines are the neighbours. For example a2 has a peering with a1 and a3. I call it the neighbours. And so on until the loop is closed. 

If I check with ntpq -pn I see 6 lines for each application server. The lines where ntp1 till ntp4 are listed have as "refid" IP addresses which are typical one of my own stratum 1 server or an external one, but with well known IP. 

And now the mystery. The lines where the neighbours ( for example a1 and a3 ) are listed shows as "refid" complete foreign IP addresses. I checked these IP's in the peerstats file of the application server but can't find it. I can't find it in the ntp server too. So where is it coming from ? 

Actually it can never be happen that a neighbour has a different group of entries. As each neighbour has the same upstream server and the same neighbours. 

Currently I see the following IP's:  238.250.161.4 187.182.182.166 51.9.218.133 
If I query with ntpdate or ntpdig none of them is coming back with a time information ?

If I look for unique IP addresses in the peerstats file of the last 10 days I have exactly 6 items. And all of them belong to my network. 

I am not new to ntp. I did deal  a lot with ntp. But this is a mystery for me. 

Any hint or tip is welcome how-to dig deeper in this issue. 


Kind regards 
Hans 









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