A canonical name (CNAME) is a type of Domain Name System (DNS) database record that indicates that a domain name is the nickname or alias for another domain name. Also referred to as the "true name," ...
The ones I may duplicate are for those records that require an A record. i.e. SOA, NS, MX. As I like to have the NS records follow a convention of ns#.domain.tld, I'll sometimes have multiple A ...