Use of DNS name resolution is optional with Cisco Unity Connection, but if available, is recommended for use with Connection. If DNS name resolution is not enabled, IP addresses (not hostnames) should be used for all network devices.
Design Guide for Cisco Unity Connection Release 7.x
I would ask you this: What was the problem you found with DNS? Is your perception that the problem was related to the customer's DNS or the UC application itself? I would guess that there was a problem with the customer's DNS. If so, has this issue been resolved?
DNS is not mandatory with either application; however, as Rob mentioned - it is recommended. If there is a problem with the customer DNS then I'd think that should be resolved regardless of what new applications are coming online.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.