The configuration file, by default, resides in the data directory (see the --data-directory parameter for further information) and is named config.toml. If you leave the configuration file unspecified, this is where MASQ Node will look for it. If it's found, it will be used; if it's not, MASQ Node will act as though it had been found but empty. But if you want to use a different file, specify it either as --config-file on the command line or as MASQ_CONFIG_FILE in the environment. If you specify a relative filename, MASQ Node will look for the configuration file in the data directory; if you specify an absolute filename, MASQ Node will not use the data directory to find the configuration file. The configuration file should be in TOML format. TOML is a competitor to other formats like JSON and YAML, but the MASQ Node uses only scalar settings, not arrays or tables.