What is the correct way to map multiple domains in a WordPress 4.1 multisite install?

I'm aware of this question and others but have not found a definitive answer to how a domain should be set up with multisite so that www and non-www variants behave correctly. I believe I have wildcards set up correctly at the DNS level and the suggested solution to add define( 'NOBLOGREDIRECT', 'http://www.example.com' ); works for my main site but not other networks in the same install.

I am using the 'WP Multi Network' plugin based on some research which led me to the conclusion that if I am running several domains on one WordPress install, I should be using multiple networks, not just multisite. My Networks and sites are all added with www included in the domain field

So what is the correct way to map bare domains without www to a multisite install? Are plugins required? Should this all be handled in web server config using rewrites?