hmm this content seems pretty dated. If they're looking at internal network enumeration, then it's missing most of the modern tools, if it's looking at external enumeration then it's not great as most of the ports they refer to are unlikely to be exposed externally...

If you want more up to date material in this kind of field, something like the Red Team Field Manual (https://www.amazon.co.uk/Rtfm-Red-Team-Field-Manual/dp/14942...) or "Advanced penetration testing" https://www.amazon.co.uk/gp/product/B06XCKTKK8/ref=oh_aui_d_... could be worth looking at.