Originally Posted by till
This was the solution
1) Good to know. But for this makes no difference for the sync tools.
2+3) The dns sync tools are suitable and will work for your problem.
I performed these steps:
1. downloaded ispconfig via svn , copied the files as you suggested in the post
2. logout and re-login ispconfig panel, appeared the new entry under "tools"
3. using PHPMyAdmin I've changed the values of ttl running "update dns_soa set ttl = 28800 where ttl = 3600" on the ispconfig db
4. I've run the Resync menu and....
..after a few seconds the bind zones files have been changed correctly
Many thanks for your help and many compliments for the wonderful job you did with ispconfig!