Can I configure master/slave DNS natively in zentyal ?
I don't think so, at least using Zentyal native GUI
This feature is not part of standard Zentyal features. Not that it has never been requested but this is not, I suppose, in the top priority.
However, with some tweak you should be able to achieve it quite easily.
Cool isn't it ?
Well, perhaps not as cool as it looks first: there is another important aspect, when it comes to expose Zentyal DNS to internet, that is missing in standard features: there is no splitDNS, meaning no split view thus you will also expose to internet you internal hosts IP
Depending on what you want to achieve, this is worth to know it before you start you design