There’s really no such thing as a “basics for an IT Manager position” as the title and duties can vary wildly depending on the needs of the organization. One org could have an IT manager who’s solely technical and keeps the hardware running (more akin to a sysadmin or network admin). Another could have that mgr overseeing all the lackeys in the department, including the person responsible for keeping the hardware running.
A manager in one org may have nothing to do with budgets and personnel, and in another, it’s all they do, and they don’t touch technology in any way. But they have to know what DHCP, DNS, and ipconfig mean in order to make sure their lackeys are doing their jobs.
I did a phone interview once for a local health insurance company for a business analyst position. I expected it to be the bridge between business units and technology, because I’m good at the Tech-to-English translation, especially when it comes to systems design and training.
What they wanted was a sysadmin well-versed in DR, load balancing, and failover. It had NOTHING to do with business analysis.
Honestly, that can be one of YOUR questions to them – have them more clearly define the position and responsibilities. You’ve already been scheduled the interview. You’re either going to nail it or you’re not. If there’s more managerial situations and you’re not a people person, then you already know it’s not the right job for you. If you’re a people guy with enough tech knowledge to know when to let the experts in your charge have free rein to do their thing, but this position expects YOU to be the 100% sole expert, then you know it’s not the right job for you.
You sell yourself and what you can do. Don’t pretend to be something or someone else, and don’t focus on what you don’t know. If you don’t know XYZ, and it’s not a top priority for them, then you’re in. On the other hand, if you don’t know it, and it’s a show-stopper for them, you’re not going to learn XYZ in enough time or to the degree of expertise that they need in the time allowed, so don’t sweat it.
This isn’t a final exam where you cram the study material, regurgitate it on the test, then walk out with your diploma, having forgotten it all.
I’ve failed many interviews, and honestly, there’s gotta be a reason why. If I got the job under false pretenses, chances are that neither I nor the employer would have been happy in the long run anyway. The jobs that I have gotten were based on the innate knowledge and skills I have. I didn’t have to study extra hard ahead of time (I’ve interviewed candidates who did that, and the gaps in their knowledge were glaringly obvious – it’s easy to spot the candidates who merely memorized answers off of a Web page and those who’ve actually done the gig).