DNS(Domain Name Servers) store records like a phone directory within your business, pointing to your email, site...
Directories hold important information, whether this is a list of phone numbers, room numbers or anything else you feel is important in this context. Your domain is the name of the directory and the DNS server is the book holding all of this information. If you change to a new book in this reference, you need to transfer all the original information into this book. Otherwise you have a blank book that’s of really no use for you or others, no details on how to find a room, person or anything else.
This is the same for your DNS servers which may look like (ns1.myprovider.com, ns2.myprovider….), these servers hold all the details. In the case of a domain, these details tell your visitors where your website resides, email and any other services tied to your domain. Therefore you can update records within these name servers and not affect existing records, but if you change the name server itself to (ns1.anotherprovider.com…), then all your records have to be copied over first. Otherwise you end up with a blank directory and all your services stop working.
DNS is THE directory for your domain, every website visit you get or email sent to you requires a look-up within your DNS directory first. It’s important to have reliable and fast DNS hosting, along with clean and correct records. Any records that are incorrect lead to delays and possibly missed visits or emails.
Should you need to make a future change, make sure to plan as this will eliminate down-time for you.