VPN DNS Resolution always resolves same external ip

Hi Sophos Forum :)

I´ve been stuck with configuring VPN DNS and the error is recurring for several firewalls now. I cannot tell if it has something todo with the V18 migration but presumably it worked quite a while.

My issue:

 

I´ve setup SSL Client VPN with the usual DHCP Pool 10.81.235 and DNS of the internal firewall interface.

The firewall WAN Interface uses Google DNS.

When nslookup server.domain.com it adds another dns suffix from my LAN and always resolves in an external IP adress rather than the internal server

For example

nslookup server.domain.com resolves in server.domain.com.domainB.com 81.17.22.33

This is the case for any host I query.

Expected is 10.20.0.5

As there is no DNS Server like ADDNS the server requested is added to the firewalls DNS entry without FQDN but its not different from firewalls where the internal server is used for DNS.

I´fe seen this on a couple of managed firewalls already but can´t figure the reason. Its really stranged that this external Ip resolves all the time.

 

Any hint is much appreciated.

 

Thanks! Marc