This is an effort that involves a lot of folks
-Sysadmins
-App folks
-Network folks/firewall
-Help desk?
-DBAs
The contingency here is at many levels. As a DBA your role should be to
-have a clean shutdown.
-take a backup
The bulk of the work here would be done by sysadmin/network folks. Oncecomplete they should ask you to bring up your database if they don't it via some oratab entry. then your app folks would tell you if they can connect or not. I'm sure others would add or subtract from this...good luck..
Looking for the greatest evil in the world? Look in the mirror.