find_prefixes from Net::IP works great and does get the work done. I don't think we require this module.

Excellent -- not having to write any code is always a good result.

But ... since you found this feature of Net::IP non-obviously, I was wondering whether other people might too. Perhaps you could submit a doc patch (with an example) to the Net::IP people, so that anybody wanting to do what you're doing can easily see how it's done?

Smylers