Multi www.domain.com addresses with DNS

[david.guillen at skwbio.com]

Hi there,

 I currently managed a domain "xyz.com", 3 sub-domains "e1.xyz.com",
"e2.xyz.com" and "us.xyz.com". This architecture is based on the fact that
we have 3 computer centers, and the administration of sub-domain is
delegated.

 For the MX records, it's ok cause I have created 3 MX records.

 I would now like to have an external www.xyz.com address, and 3 differents
internal www.xyz.com addresses regarding the site where the request is made.
Is it possible ?, what feature of DNS may I used ??.

 Thanks for your help.

david.guillen at skwbio.com