DNS Record

[Me.B]

Beside, the NS record that is created after the step above is always ns1.mynewlyaddeddomain.ext & ns2.mynewlyaddeddomain.ext instead of my server nameserver.

What do you mean? Do you have other name servers??

You need only to create dns record if you intend to use your OWN DNS servers as primary/secondary DNS. 

Often you are already using your registrar dns, so you don't need to switch. Don't get confused here as you can keep using your registrar DNS and create  the dns entries there not in sentora panel.

M B