Below is excerpt from the README in the domain access module. To set the advanced usage (means that the domain editor is not only one administrator who can edit/delete all the content if necessary. The domain editor can access the contents belong to the same domain).
In Readme.txt
3.3 Advanced Usage
In the event that you wish to segregate which content certain editors can control, you should not use the normal 'edit TYPE nodes' permission provided by Drupal's core Node module. This permisson grants the ability for a user to edit all nodes of a given type.
In the Domain Access model, this permission is not used in favor of the provided 'edit domain nodes' permission. This permission allows editors only to edit (and delete) nodes that belong to their subdomain.
To enable this feature, you should grant the 'edit domain nodes' permission to some roles. Then you should enable the 'Use access control for editors' setting under the Domain Access configuration screen.
