On the network level, seems to have missed the ARP protocol entirely. Didn't seem to mention the function of the multiple routers between client and server, the calculations of netblock and subnet mask, role of firewalls between client and host, etc, etc.

Probably missing off the top of my head at least 100 steps. If you sat down to write a paper on it he's probably missing closer to 1,000 discrete units of work in the overall process.