I have a website say example.com with 5 sub-domains(site1.example.com,site2.example.com,site3.example.com,site4.example.com,site5.example.com)

When a user visits example.com,he is presented with the other 5 sub-domains to choose from.I want to implement something like, when a user selects say site1.example.com,on his next visit to example.com he should be re-directed to his previous visited (sub-domain) or link he selected(site1.example.com).I know u can use cookies for this but how do you go about this in drupal.

Any help will be very much appreciated.

Thank you