[lug] url redirect through dns

[charles at lunarmedia.net]

i have a client who has two domains pointing to one website. within dns,
they both resolve to the same ip address. the client considers one of the
domains to be more of a marketing ploy rather than the primary domain. he
would like users typing domain2.com in their browser to reach the website,
however to have the address rewritten in their browser as domain1.com.

i think this can be done through the apache config, but i'm not sure how.
anyone know?