Routing everything to https://www.domainname/ on AWS ALB

I'm using a DreamHost registered domain for an AWS-hosted site.

AWS site consists of an application LB listening on 80 and 443, forwarding to two EC2 instances on 443. LB uses an AWS ACM cert for both domaninname and www.domainname. EC2 instances use ubuntu 16.04, apache and self-signed certs

The only DNS record I created is a *.domainname CNAME record (at DH) pointing to my AWS app LB.

Questions:

1. why is http://domainname redirecting to http://www.domainname? (I'm not seeing www in any apache config file, and the sole DNS record isn't doing it)
2. given 1, why does https://domainname not redirect to https://www.domainname?
3. why does https://domainname return Server Not Found?

Details below in a follow-up comment (including things that I've tried)

Thanks in advance