From experience, I can tell you what most IT companies are going to ask you if you apply for a job.
First, if your going for a corporate IT job, the interviewer is going to quiz you first on your knowledge of the OSI networking model. An IT tech who doesn't know the OSI model (at least a solid understanding of the first 3 layers as well as the application layer), won't get very far in the interview process.
Secondly, you will be quizzed on subnetting. I can't tell you how many interviews I had where the prospective employer handed me a piece of paper and a pen and told me to subnet an IP address. He would give me a network ID and tell me to subnet that address into 20 subnets with 32 hosts per subnet (just as an example), and to list the broadcast IPs for each subnet.
Those are the 2 things I've encountered the most looking for a corporate IT position. There will be exceptions, but if you want some real world advice...
Learn the OSI networking model inside and out and learn to subnet well enough that you can do it in your sleep. With those 2 things in your toolkit, getting a job in the IT world will be much easier.
Also learning windows based networking operating systems as well as linux will make you a more attractive prospect for employment.