I have been working on DNS server, with ubuntu server, bind9, my public ip and my domain.
I finish configuring the zone and everything in the webmin, and it does not return errors, the problem is that after doing nslookup in the cmd it does not return anything,
So I think the problem is the redirect
I attach the images of my modem and configuration of ens38 of ubuntu
I hope you can help me, since I can not find the functioning of the server
* The ip with which I open the ports of the modem is free in my lan
* The gateway of my modem is 192.168.0.1
* I have the public ip tied to the modem.
* The ip that comes out in the ubuntu 192.168.0.20, is the same one that opens the ports.
* In the nameservers my public ip goes
PDS: in a comment you will leave the ubuntu photo 
That's what's on the ubuntu in the / etc / network / interfaces in the ens38 part