What certifications do you have?
I don't have any, I think certifications are a great way to show your skills and get a job but I have not needed them myself for my career so far. I will get some one day.
What is your favorite OS?
Ubuntu is my go-to for a lot of tech work and always will have my top slot just because of nostalgia. Mac OS and Windows are my daily drivers due to ease of use and most programs I need are available on them. Almost all my servers run Ubuntu, Debian, and Windows.
Can you diagnose my computer?
Most likely not over the internet, there are too many issues that give the same symptoms and so without having it in my shop and testing it I would not be able to give an accurate diagnosis.
Where is your shop?
I don't post publicly where it is, and if you are asking you are most likely not close enough that it would be helpful.