is this possible

[me]

I was wondering if I could make my subdomain point to my domain,
I am trying to set up multisites using postnuke. The subdomains need to point to the same directory as the main site, where postnuke is installed.
heres what i need to do,
I need sub.domain.com
to point to domain.com
postnuke needs to recognise that the site was accessed through sub.domain.com so it will use the right file
Is this possible?