I assume that if I do not have custom nameservers and I am using the nameservers at the host of my domain name that I should turn off the plesk DNS? Does it matter if I just leave the plesk DNS on anyway? Surely at worst it is just redundant and causing no problem? What is the advantage of turning it off? Can turning it off cause a problem even though the DNS zone (A records etc) are located at my domain name's host?