It works by connecting to the local powerdns database to retrieve a list of published zones. For each zone it uses axfrdns to retrieve a copy of the zone in tinydns format. It then compiles them into a single cdb database file suitable for tinydns and uses scp to copy that to each slave server.
As a performance enhancement it uses an MD5 hash of the combination of zones and checks whether each slave is already up to date before pushing out a new copy. This makes it suitable to run regularly from cron, even for large, mostly static dns.
Out of the box it will work with Postgresql-backed PowerDNS, but with minor modifications it could be used with any master dns server that supports AXFR.
It's configured by editing the script. The main prerequisites are