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.