Hi Manjunath,
Your redirect URL does not have to be landscape specific. It can be relative. Like- Redirect URL:
/sap/public/bc/icf/logoff?redirecturl=/company/itsmobile/servicename
"/company/itsmobile/servicename" is the path (under 'default_host') to your internet service which is the same is all systems.
This way, you do not have to change the URL in different systems. Just transport this change through to Quality and Prod.