[ntp:questions] NTP servers not accessible on some networks

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Wed May 21 02:27:07 UTC 2014

Antonio Marcheselli wrote:
> Version is 4.2.4p (yes, I know. It's the same version I've been talking
> about and I cannot upgrade it unfortunately).
> When running ntpq -p I've got this
> xxxxxxx-2:/etc# ntpq -p
> remote       refid  st t when poll reach delay offset jitter
> ============================================================
> .INIT. 16 u    -   64   0   0.000  0.000  0.000
> xxxxxxx-2:/etc# ntpdate
> 20 May 23:30:11 ntpdate[16690]: no server suitable for synchronization found
> The same works from other networks.

It appears your client quries are not making it to the server,
 or answers from the server are not making it back to your client.

Seems like an issue with your client PC, PC Firewall, ...,
 or client NTP .conf, or LAN Firewall / Router rules,
 or ISP  Firewall / Router rules.

> If I keep pinging different pools,
>  I can find another NTP server which replies.

Seems strange, that would imply that the server
 (or their ISP) is blocking your client?

> Question: if I use the pools and for some reason the current server is
> not reachable, when the server is changed will NTP update and start
> using the new server instead? Or will NTP needs to be restarted?
> In other words: if my server boots up when a non-reachable server is
> linked, will it keep the same unreachable one till next reboot?

IIRC 4.2.4 (4.5 to 6.5 years old)
 on startup, if the servers are defined with host names e.g.:
  server pool.ntp.org, server 0.pool.ntp.org,
  server europe.pool.ntp.org, server 0.europe.pool.ntp.org,
  server de.pool.ntp.org, server 0.de.pool.ntp.org, ...
 it will get IPs from the pool at startup,
  but not replace them with new IPs from the pool later
   if they get discarded.

With a more modern 4.2.7 circa 2010Apr or newer,
 if the servers are defined with host names e.g.:
  pool pool.ntp.org, pool 0.pool.ntp.org,
  pool europe.pool.ntp.org, pool 0.europe.pool.ntp.org,
  pool de.pool.ntp.org, pool 0.de.pool.ntp.org, ...
  and restrict source
 as it discards servers, it will keep getting more IPs from the pool.

It might help other figure out your issue if you show your ntp .conf
 maybe you have some errors?

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