Well , looking at your query since you are using the your domain registrar's default name server you will have to add the A entry of any domain or subdomain accordingly as the DNS zone of that particular domain is not hosted on your server.
If you want to avoid these things .. you need to create your own name servers, register them at your registrar , assign those name servers to your server too , this will avoid the hassle of manual addition of DNS records as you have specified