A subdomain is technically defined as when you assign a different section of name servers for part of a domain. For instance “dnsmadeeeasy.com.” is a subdomain for “com.”. Creating “sub.dnsmadeeasy.com.” on a different group of name servers than “dnsmadeeasy.com.” would be creation of a subdomain. In contrast, “www.dnsmadeeasy.com.” is a record with the name of “www” within the domain “dnsmadeeasy.com”.
You would create a subdomain for “sub.dnsmadeeasy.com.” rather than a record if for example, “sub.dnsmadeeasy.com.” will be assigned to different name servers than “dnsmadeeasy.com.”
We will create the subdomain “sub.example.com” as a subdomain of the root domain “example.com” and delegate it to the name servers ns0-ns4.nameserver.com.
Step 1: Select Managed DNS
Step 2: Select a domain
Select a domain from the either the “Recently Updated Domains” box, or start typing the domain name in the textbox on the “Select Domain” tab.
Step 3: Add an NS record
Scroll down to the NS records for the domain and click on the plus sign to add a new NS Record
Step 4: Insert NS values
Create additional NS records that delegate “sub” to each of the name servers it will be assigned. Each name server host name must end in a dot (.) to keep your domain name from being appended to the end.