domain migration

Hi,

I use a domain aaa.bbb.cc in a C class IP
since few years.
I must modify this domain with aaa.ddd.ff.
But during few months, I must use the 2
domains aaa.bbb.cc et aaa.ddd.ff.
For example, if a user connect to the machine
pc1.aaa.bbb.cc, he must be redirected to
pc1.aaa.ddd.ff.

Do you know the better solution to do this ?
Is there an easy way to create a link beetwen
this 2 domains (like symbolic in unix) ?

Thanks by advance.


--
Eric Bordenave.