If you install and configure the OWA Extensions on the passive node first, running the Enterprise Vault OWA configuration wizard will do the following:
Create in Active Directory the following Exchange Server virtual directories for the back-end Exchange Virtual Server:
Create the following IIS virtual directories on the passive node computer:
Populate the Proxy bypass list on the passive node computer from the file, Enterprise Vault\OWA\EVServers.txt.
Note that forms registration is only performed when you run the Enterprise Vault OWA configuration wizard on the active node. If you examine the log file, Enterprise Vault\OWA\BackEnd200nSetup.wsf.log, after the configuration wizard has run on the passive node, you will not see any forms registration lines.