Reverse Lookup external DNS

[hgfm]

Hello,

we run an external DNS in our DMZ. The forward lookups work perfectly with these lines in /etc/bind/local.conf.samba4:

# add local zones here
zone "dmz.domain.com" {
  type forward;
  forwarders { 192.168.120.55; };
};

We tried to get the reverse lookup to work with these lines, but unfortunately it doesn’t work:

};
zone "120.168.192.in-addr.arpa" {
  type forward;
  forwarders { 192.168.120.55; };
};

What settings do we need to make it work as desired?
Thanks!

[hgfm]

We got it working with this config:

zone "120.168.192.in-addr.arpa" IN {
  type forward;
  forwarders {192.168.120.55; };
  forward only;
};