how to control URI router ON or OFF?

[eluser]RING[/eluser]
i set router in /app…/config/routes.php

Code:

$route['member(.*)'] = "member$1";
$route['(.*)'] = "home/$1";

my website bind 2 domain-name :
domainA.com
domainB.com

when people visit my website by domainA.com,
i want the router worksrouter setting ON)
http://domainA.com/someword ---> class :home , methodomeword()

and,when people visit my website by domainB.com,
i want the router DO NOT workrouter setting OFF)
http://domainB.com/someword ---> class omeword , method:index()


is it impossible ?