It's a broad topic. My dergree is in electronics and music (BEng Hons), but it was a while ago. I do keep up on music tech though.
What could they ask? Hardware and software, some covering the same or similar functionality.
Try breaking it down into categories: performance tech, recording and production tech.
performance tech covers outboard effects like stomp boxes and multi effect controllers, amps, keyboards, control surfaces, samplers, microphones, live mixers too.
recording and production is far wider, covering computer based tech, and dedicated outboard hardware. DAWs like Sonar, Cubase, ProTools, and other Mac and PC based sequencers, drum machines, VST plug in effects, treatments and processors, EQ, audio formats, filters, 3D sound, audio perception, acoustics, studio design, VSt and other synths and samplers, Midi, plus tools like rewire, understanding individual effects and treatments from reverb and delay through compressors, noise gates etc. plus algorithm based noise reduction and mastering tools, amps and amp simulators, wave editors smpte and other sync interfaces, microphones, audio consoles and much more. Depending on the emphasis of your course, questions could range from usage scenarios, to tech theory, to design and implementation. Even simply know what exists and where and when you might use them is a good step. It helps give you an overview of the range of music tech.
Awareness of key effects and treatments, for example EQ types, reverb, delay, enhancers etc is key knowledge. Understanding the principles of mixing and understanding your way around audio consoles is well worth understanding.
I hope this helps.
Sounds, like a lot and it is.