Configure so that UCS does not resolve DNS and forwards it to the external Firewall to resolve

Some help please. I have a Firewall server configured on the network, I installed UCS and I want it to not resolve the DNS, which forwards it to my Firewall to resolve, as I already have the rules and blocks ready there.
Example: My UCS is at IP, I can place the machines in the domain, and I want the person who resolves the DNS to be my Firewall at IP, but as it is in the initial configuration, the UCS always resolves it. Thanks

you could set the external dns-server to your Firewall

ucs set dns/forwarder1=""

as described as in 8.2. Configuration of hardware and drivers — Univention Corporate Server - Manual for users and administrators everthing outsite of your domain gets forwared to this dns server