but now it totally looks different from ispconfig 2,
Sure, it is a completely different software.
To add a dns record, login to ispconfig, go to the dns manager module, click on the dns wizard > add dns zone, enter the domain "zambahotels.com2, the promary and secondary dns server and the email address and click on save. Thats all.
By the way, this is not related to the /etc/resolv.conf which is the topic of your thread.