DNS setup affecting page rank?

[CaptainJSparrow]

I'm seeing the www version and the non-www version having different page ranks on lots of my sites.

I've asked our new host about this and they said:

Normally, when we setup a site in DNS we set the domainname.com as an A record to the IP address. Then we setup www.domainname.com as a CNAME pointing to domainname.com. So, on the DNS server it would appear like
this:

Method A:
domainname.com A 12.345.678.90
www.domainname.com CNAME domainname.com

This essentially means that to a client (from a DNS standpoint),
domainname.com and www.domainname.com are the same site. However, this is how you currently have it setup (btw our tech did this):

Method B:
domainname.com A 12.345.678.90
www.domainname.com A 12.345.678.90

This could confuse google if they are using DNS alias information to determine if a www is an alias or a different site.

My question, which method is the correct way, which is better, or are they both the same.

I am concerned that with 1 of the above methods that googlebot may think that 1 site is actually 2 different sites and penalize either, or both, for having duplicate content.

Let's call the way that our new host recommends the sites be set up, Method A

and the way that our tech set them up Method B.

Does anyone know for sure which method is best?