For any server usage, you want to use NetBSD without access to keyboard, mouse or monitor. For these usages, you want to have access via ssh (or something similar, document that) or serial console.

Your task is to describe the steps which are necessary to run a NetBSD system headless, i.e. printing boot messages to serial port, enabling the bootloader on serial, enabling the serial port, describing the possible options how to do so, which security measures should be taken.

You should also consider systems which don't even have a serial port, i.e. what has to be done if you cannot watch a device start, but you must go sure it will come up and you have some sort of access (like a router).

Our preferred format for the submission is some form of plain text, as that is most portable and can be read anywhere.  If you want to use a word processor, please export the file as text.  You could also add something like markdown or latex to add structure (these are both plain text based), but that is not a requirement.