Learn these before day one
The candidates who struggle are almost never short on enthusiasm — they are short on networking. Before the course starts, be comfortable with the TCP/IP model, what a three-way handshake looks like in a packet capture, subnetting, DNS resolution order, and HTTP request and response structure. Add basic Linux: navigating a filesystem, permissions, processes, and reading a log with grep. A fortnight on those makes the difference between following module 3 and copying it.
