I have personally sat on interview panels with regard to positions for AD related Administration. Of course, the questions would depend on the job duties since they may vary, but I would recommend that you focus on the key AD related concepts such
as:
The logical structure and objects found in AD (sites, services, OUs, computers, users, etc...), types of Name resolution that occurs on a network (DNS, NetBIOS), IP managment (static and DHCP).
You may want to try to find out what other networking services this company has in place... Messaging, Remote Access, Antivirus, Firewall, Proxy, etc...
When you respond to the technical questions, I would recommend that you try to include an example of your experience. For example, If the question is about designing AD, answer the question technically, but also give an example of when you were last
involved in designing an AD forest.