Usually they will list specific technical knowledge that you should have in job advertisement or job description. This is what they are likely to ask you about.
Generally military training in these areas are superior to industry training and military trained professionals and trades people are often highly sought after in industry for this reason. Industry also appreciates the discipline and work ethic many people from the military show.
From experience some people list years of computer or network experience, but give vague answers to computer questions. Just be honest with your answers. You really will only have a problem when you are claiming to know something that you don't know. In the IT industry we are more interested in people who can learn quickly or by themselves, rather than have to trained in everything.
The questions to worry about are not so technical. They are likely to be about your ability to solve problems individually, as part of a team, ability to self learn and your communication skills. Examples from the army will work here, because they will be different and make you stand out from the crowd.
The main issue would be you ability to fit into the corporate world. They may even ask a specific question about this. They aren't anti-military, but they would worry that maybe your don't know how to act in a normal workplace (seriously, it is common issue for people transferring between industries, countries or types of workplaces).
Don't worry, relax and good luck.