I'm adding a new server to an existing SharePoint 2010 farm.
Does the new server have to be installed using the same product key as the other servers? And does the new server have be updated up to the same SharePoint build as the existing farm servers before being added to the farm?
Yes, you should use the same key. And yes, you should apply all the patches required to match the other servers in the farm. If you don't you won't be able to add the server to the farm. And, you'll be prompted to apply all the necessary patches before the configuration wizard can complete successfully.
