No worries. My English isn't clear either and I am from USA.sorry if my english is not clear
There are lots of ways to do it. Let me give you some simple parts first.
For every DirectAdmin (DA) server, you have installed you have Master DNS as well. They all can share Zone files between them by using MultiServer Setup (MSS). So if you had 2 DA servers they are effectively or could be NS1 and 2 because each DA server is a DNS server as well. Make sense?Do I have to use two separate DNS servers?
I could have two VPS master, one with ns1 and another with ns2.
Now if you don't need to or don't want to have more DA servers but need more DNS separation or help in that area. You can add slaves. Which wouldn't have the DA control panel installed. This would be just 1 or 2 very small VPS that have some type of DNS server software installed like DirectSlave or PowerDNS.and then add slave to them.
Is this helping or more confusing? You might want to hire it out if you're not sure.