The "different files" you refer to are likely just different distros ways of configuring scripts that use netlink/ip. Each distro will do something differ, or use something like systemd-networkd/networkmanager. There's no one way.
netlink is the API, and `ip` is the canonical CLI tool for interacting with the tool.
netlink is the API, and `ip` is the canonical CLI tool for interacting with the tool.