Sometimes when the file share that is hosting the witness gets taken offline the exchange server will report that the File Share Witness has failed and it will not be able to bring it back online and give back the reason "Access is Denied"
You know full well that the share permissions have been set properly, giving the Exchange Trusted Subsystem Full Access to the share and adding the same user to the local Administrator group but it still doesn't work.

By putting your Exchange server(s) into maintenance mode you are allowing the servers to stop processing all incoming mail and drain anything that is still in the pipeline.
Why would you do this? For 2 reasons. Updates (both Windows and CU's) and to redirect all traffic to other Exchange servers in your environment.

I like having a centralized time source for my clients. In a Windows based domain 99.9999999% of the time you will configure your domain controller(s) as the NTP server. In other words, your time source for everything in your network/domain.

And this is how you do it...

Migrating DHCP servers is actually quite easy to do and isn't that complicated. If in a situation where you have multiple DHCP servers for failover, it doesn't take that long as you only need to migrate one server and set the rest as failover and by doing that it will automatically replicate the settings.

I'm personally a big fan of using Server Core because of it's low footprint and the amount of updates there are compared to the desktop version. So this guide will mostly involve powershell commands, but can be used with the desktop experience installed as well