So, let us say that we have set-up an A record and an AAAA record for @, and for www we have set-up a CNAME pointing to @.
When a new visitor visits example.com and the webserver sends a 301 permanent redirect to www.example.com, will that still require an extra DNS lookup after the CNAME, even though it already knows @'s location?
If so, why do many companies use the CNAME method over an additional A and AAAA for www?
Finally I would like to mention that I have searched through the whole internet for an answer to this question.