Lets say I have 2 domains, A (Site A) and B (Site B). I achieved this with domain access module. Then with features and strongarm I would like to export
site_name variable from both domains. How can I do it?
What you want is the Domain Conf module which is a sub-module of Domain Access and provides you per-domain configuration.
The Domain Access: Site Configuration module (called Domain Conf), is an optional extension of the Domain Access module. Domain Conf provides options for configuring basic settings of your affiliate sites to be different.