Tumblr's doc 'Using a custom domain name' is quite helpful it that it clearly states that I need to create an A-record for example.com pointing to 66.6.44.4, so that my website is accessible via example.com.
But I don't understand this: How do I make www.example.com take the user to example.com?
It goes without saying that this needs to be done via DNS, in a Tumblr-compatible way (just in case there are any incompatibilities).
From searching, I read that it's NOT possible to redirect example.com to www.example.com. I can only hope this is NOT true.
If, unfortunately, it happens to be true, my only option is to create a CNAME record pointing www.example.com to domains.tumblr.com - isn't it?
Ah! As stated in this answer, you need to create two DNS entries as such:
example.com to 66.6.44.4www.example.com to 66.6.44.4I checked the domain in the answer - emmaraviv.com - apparently, www.emmaraviv.com redirects to emmaraviv.com. So yeah, this is it!
You need to create two records, an A record for the two-level domain (example.com) and another A record for the three-level domain (www.example.com), then add example.com in Tumblr > Settings for your blog, and now example.com should redirect to www.example.com without a hiccup — as far as I can see it.
UPDATE: Just tested this with my blog, and yes, I can confirm that it works!