The registrar I have is networksolutions.com, and for quite a while, the name servers were pointing to Site5.com, where hosting is for one of my domains. I wanted to bring DNS control back to networksolutions, so I pointed the name servers back to networksolutions and added in all my A records.

However, I noticed that the site soon became unreachable. I'm curious as to why this happened? If the domain was pointing to either the old name servers or the new ones, it would still have the proper A records and whatnot.

Is this because when I changed name servers, a request was made to delete them completely, and then the DNS servers worldwide have to wait for network solutions to send out the new ones or something?

I was hoping this would be a switch with zero downtime, such as a normal A record change.