Set the options, copy the file, drop it next to your server jar. No more guessing the property names.
Set online-mode=false only behind a proxy (BungeeCord/Velocity) — never on a public server, or anyone can join as any username. Lower view-distance (8-10) to cut RAM/CPU on busy servers. Need a place to run it? Managed Minecraft hosting sets sane defaults for you; or size it with the RAM calculator.
Straight answers.
In the same folder as your server jar. It's created on first run; this tool gives you one to drop in or edit.
When true, the server verifies players against Mojang/Microsoft auth. Only set it false behind a proxy on a private network.
8-10 is a good balance. Higher loads more chunks (more RAM/CPU); lower improves performance on busy servers.
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