This probably comes under the heading of dumb questions. Due to changes in Australian TLD eligibility rules, I have to change domain names from a .net.au to a .net, as the name server is currently NS1.XXXX.net.au, NS2.XXXX.net.au but it will have to become NS1.XXXX.net etc. Do I have to ask my domain name provider to delete the original NS1.XXX.net.au and NS2 name server from the global registry before adding NS1.XXXX.net and NS2 so there isn't a clash with the ip address and the name servers? That is having 2 different name servers on the one ip, looks to me like it may be trouble.
No, just add the new nameservers and set them as authoritive. You can point as many hostnames as you want to one IP.
