I have an internal DNS server running on a VM. I've rebuilt the server from scratch in a new VM, and I want to cut over from the old to the new at some point. In order to do this, I'll need to take down the old server bring up the new one with the same IP as the old one.
I'm wondering what is the best way to do this without disruption. How quickly will the other machines on the subnet work out the new MAC address of that IP? I know I could accelerate this by flushing the arp cache on them all, but I don't have an easy way to do this on all boxes at the same time. I'm wondering if "nmap -sn 192.168.101.0/24" (i.e. ping all hosts on the subnet from the new box) will speed up the change?
Alternatively, being VMs I could set the new one to have the same MAC as the old one, but I'm concerned that the switch might get upset about this. Is this a better way to do it, and if so, what do I need to watch out for?