How Subdomain works (for documentation)

[moglia]

I will starts produce of end user documentation anyone can explain how subdomain works im looking at apache alias points subdomain for the same document root of main site.

Host
DOMAIN
REDIRECT TYPE - No Redirect - No Flag - R - L - R,L
PATH

Active - Y

I need explanations how REDIRECT TYPE works.
it´s possible create a independent virtualhost for subdomain?
(see workarround)

How subdomain can use another document root.

domain inclusion creates folders: cgi-bin log ssl tmp web

subdomain can use a folder like: subdomain name?

at the same level of web (document root)

cgi-bin log ssl tmp web subdomain

The main question is can specify another document root for subdomain?

If not possible specify a subdomain document root i no see any diferences between server alias and subdomain.

i think alias can redirect one domain to another using virtual redirect. one domain to another.

My workarround i created subdomain as independent website.

My idea is create subdomain with another document root with the same virtual hosting settings. share setting (main domain and subdomain).