While installing the ESXi 7.0 Update 1 on one of my physical system, I happened to be in the "Configure Management Network" section of the ESXi Direct Console UI (DCUI) and noticed something I had never seen before. As shown in the screenshot, it now shows the IP Address of the DHCP server in which ESXi received the DHCP lease.
I had not noticed this before and after asking on Twitter, it looks like this is definitely a new enhancement that was added fairly recently. I did not see this in one of my ESXi 6.7 Update 3 deployments, but it may have came in a later patch but definitely new in ESXi 7.0 or greater. Not only is this a quick and easy way to identify the DHCP server being used but in case you need to track down an unexpected rogue DHCP server running, this will certainly come in handy as pointed out by John.
Trying to get rogue DHCP servers under control?
Remember kids, DHCP Snooping saves lives! https://t.co/FKPgKzI9In
— John Nicholson (@Lost_Signal) November 20, 2020