What are DNS (primary or secondary) servers and how to get them?

A primary DNS server is the server that store the original zone file of a domain name. Any change or update to the zone information is done through this server that also responds to any inquiry about the domain name. While a secondary DNS server gets a copy of the zone file from the primary DNS server. It responds to any queries about the domain name but it does not do any update or change to the zone information directly. You can get DNS servers from ISPs, web hosting service providers, or from your entity’s IT department.