What does a Primary DNS server mean?

If you could have an x-ray of the Internet or any other network, you could see how servers are the keystone for them to work. The amount of them and the tasks they comply with are vital for these systems’ existence. 

What does a Primary DNS server mean?

It’s called Primary DNS server or Master DNS server. These names indicate its importance since it’s the source of all the original data for a specific DNS zone and its corresponding domains. A Primary DNS server is responsible for storing all the DNS records for its DNS zone. Therefore, every time a record (or more) requires a change, edition, or to be deleted, that can only be made in the original source, the Primary DNS server.