When learning about SEO, you have probably read that you should only use www or non-www and only http or https. This begs the question: What does “only” even mean? Does it mean in all your blogs and PR events you must link consistently to https://www.example.com or is a forward from http://example.com to https://www.example.com good enough? My research for this suggests that a forward is enough and you do not need to worry, as long as you register all the versions of your site in the Google Search Console.
Nowadays if you have a somewhat potent webapp, you probably need users to login and therefore you need SSL (https). Whether you use www or non-www doesn’t matter as long as you are consistent. Quora.com redirects to www and stackoverflow redirects to non-www, so you have examples of two sites that are good at SEO with different settings.
Now lets say we want to setup our www https page. What we can’t do is a 301 permanent redirect on the registrar, since they can’t redirect https non-www. So we will have to write the redirects on our own servers. So in the end we will have:
A record: @ pointing to <my_IP> CNAME alias: www pointing to @
while the redirects non-www to www and http to https happen on the server. Here is an example for how to redirect from http to https using nginx.