Forward DNS-server sometimes dissapear

UCS - Univention Corporate Server
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#1

Hi there,
my ultimate goal to replace my Windows Server with UCS for my homelab has been achieved and I’m quite happy with this. But while I was playing and testing around prior to the migration I’ve observed an unexpected behaviour in my network settings.

I’m using two (2) pi-hole as forward-DNS-resolver to filter ads, spam, … whatever pi-hole is able to filter out with public lists.
The IP-addresses of these two pi-hole are stored in the network settings under “External DNS-Server” and all the DNS-requests that the UCS are facing are beeing processed by the pi-holes.
Sometimes, especially 2 times after an update has been performed, the external DNS-Server are gone and the network traffic stopps. This is, because the gateway is accepting DNS-requests only from the pi-holes, all other devices are blocked by a firewall rule. So everything works as designed, apart from the network settings that is loosing the Extrenal DNS-Server sometimes.

Is there anyone else who has also observed such a behaviour?

#2

I see also some strange DNS things happening with UCS Servers
while the external DNS forwarder is configured as my OPNsense Firewall, UCS tries to reach the following DNS Servers, which are not configured anywhere:

grafik

Don’t know how this happens and where the source of this behaviour is.
The result is that sometimes the clients get DNS lacks (long time responses, as ZENARMOR blocks the destingation DNS Servers UCS tries) as the internal DHCP is configured to set the UCS Servers as the default DNS Server Client side

rg
Christian

#3

Just to let the UCS team know: With the latest update my forward-DNS server dissapeared again.

#4

I‘m proud to announce, that my Forward-DNS entries have been kept with the recent Update!

#5

Ok, once again: On my primary node the forward-DNS server (=pihole) are gone, on my backup-node the forward-DNS server are still there.
To me this seem to be a bug that appears randomly.
Latest build has been installed.
I’m lost, don’t know what to do …
Can not check every day if the DNS-forwarder are set or gone …

Any ideas?

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