I'm going to be interviewing for a 'Trainee' post shortly - I'm not expecting them to know much about Networks as the idea of the 12 month contract is to give them an overview and hands on experience etc.
I'll probably stick to basic A+ type scenarios on a PC - such as a loose memory stick and setting up local user in XP. That type of level should give us an indication of what they know, but more importantly how they tackle it. ie will they give up, ask questions or try and bluff it. I look at the practical tests as a guide to how they would cope under pressure.
The full extent of the applicants knowledge can be judged through the interview process.