The company I am working for is changing the name servers our registrar points to and wants a complete impact analysis in worst case scenario to impacted systems.
I know if we update the TTL's and wait approx 48 hours for replication and then duplicate all entries on old and new name servers update registrar to point to new servers and leave both servers up and running until replication from old to new has occurred there should be no down time but they are interested in worst case.
The worst case scenario is that there is a typo when updating the name server and it points to a none existent name server and is not detected until 48 hours later.
Now their biggest concern is how this will impact Microsoft Office 365 services... specifically how often does Microsoft check for the txt ownership of domain record and is there a possibility all of business could become locked out of O365 etc. because Microsoft checked and decided you no longer own the domain while the name servers couldn't be found. Does any one have experience with that kind of outage and can say if O365 would go down? I can't find specific Microsoft docs on this topic which Business would prefer to see. Has anyone else come across Microsoft docs specifying these details?