Hello,
DNSmanager saves its in the /usr/local/mgr5 directory
You need to copy and archive that directory. Besides, make sure that DNSmanager uses named or powerdns, you need to save these data.
If you need to make a backup copy for import between servers, you can save only the main database
/usr/local/mgr5/etc/dnsmgr.db*
and the base of IP addresses
/usr/local/mgr5/etc/dnsmgr_ipdb.db*
Documentation