code: function getFqdn(hostidentifier, cb) {
    if (os.type() !== 'Windows_NT') {
      throw new Error('Package currently not-supported on non-Windows platforms.');
    }
  
    if (net.isIP(hostidentifier)) {
      getFqdnForIpAddress(hostidentifier, cb);
    } else if (hostidentifier.toLowerCase() == localhostIdentifier) {
      getFqdnForHostname(os.hostname(), cb);
    } else if (hostidentifier.indexOf('.') == -1) {
      getFqdnForHostname(hostidentifier, cb);
    } else {
      // hostidentifier is an Fqdn, just return it.
      cb(null, hostidentifier);
    }
  }
docs: Handles IP address, hostname, localhost or FQDN.  Signature of cb is: cb(err, fqdn)