We have a Viprion c2400 f5 dns with 3 vCMP guests dns. does it mean I need to upgrade each alone? or does the upgrade occur on all when done in one?
Yes, you have to upgrade each separately. I think there's option to upgrade all at once, but its not advised as its CPU extensive.
Also you have to consider upgrading the host 1st before starting the guest. There are multiple articles around, refer them.