Tryhackme helped me land a job. I found nothing better in studying for technical screenings and getting familiar with new tools. Certs are great and all, but thm is a proving ground with their rooms, and king of the hill competitions.

I haven't looked too thoroughly, but this looks great. I'm kind of surprised they don't have CASB, tho.

Some of their modules are great for learning the basics. Their forum is atrocious for being a Cybersecurity training platform. Spam Galore.

https://tryhackme.com/forum/

see also RFC 2828 and 4949

https://www.ietf.org/rfc/rfc4949.txt