Roll back to to the previous state of the hosts file 
for this domain

     If for some reason bad data gets put into the 
hosts file that you are editing, and you would like 
to revert back to the previous version of the hosts 
file, you can do it by making this selection.  
This selection causes DNS Boss to:  copy in the 
previous version of the hosts file for this domain, 
and remove all DNS databases, and then rebuilt all 
DNS databases.  This removes any old non-existing 
DNS data.

     The rollback gets the previous version of the 
hosts file even if you are in a new GUI session.