Unless someone else can answer authoritatively (I'm not downloading ActiveState just to view the source of this module, and it's not available on CPAN), I would suspect that this function would assume the domain of the user running the script, or the domain of the currently logged-in user. The documentation on ActiveState's web site makes no mention that this might be an optional argument. If you have the means, see if you can determine the behavior by examining the source.