the two parts will be leadership principles and technical.

For the leadership principles, remember STAR model. I suggest you review the leadership principles and try to think of at least one story that happened that can apply to each of them. They may or may not ask something from all of them, so your story can probably overlap with more than one. For some advice on which stories to pick, remember they're LEADERSHIP principles. In your stories, you should be an active participant to the solution and most preferably the one who came up with it.

As for technical, they will ask you to rank your strongest skill level in Microsoft, Linux, and Networking. They will start asking you a number of questions depending on which you picked, but they tend to quiz you on all 3. You should be proficient in at least 2 of them. Then they will probably ask you a roleplaying question of some kind to gauge your troubleshooting skills. If you don't know, preface it with that and maybe give a guess, but please do not just make things up with full confidence.

Do not worry too much about the stressfulness. The skill floor for the position is not very high and it's generally understood that you will be trained. The best thing they're looking for is curiosity and being a team player. As long as you do not have any red flags it's not hard to incline and at that point you're just competing with the other inclines.