I am a moderator at Drupal answers, and migrated this questionthis question to SF a few days ago. I migrated it because it didn't really have anything to do with Drupal or Drupal configuration. It is essentially about getting Plesk to map different domains to the same directory, each with their own IP address.
What in particular about this is off-topic? Is Plesk considered a non-professional environment, and therefore off-topic?