Use custom db.cache file

     In some cases it may be desireable to  use a 
custom db.cache file.  This could be done if there 
was a need to maintain DNS for an isolated network 
not connected to the Internet.  The standard 
db.cache file is a list of DNS servers on the 
Internet that are at the very top level of the DNS 
tree.  In the following example:  
"www.some_company.com." the final "." is the 
equivalent to all of the machines in the db.cache 
file.  The final dot is not generally referred to 
because it is understood, but it does exist.  To 
better understand what "." is, try the following 
experiment:  

% ping  .
.  is alive
%

When the system says ".  is alive", it is saying 
that one of the machine in the db.cache file, at 
the very top level of the DNS tree, is on the 
network.  

     The standard db.cache file is always used by 
DNS Boss by default without selecting anything.  
You must select "Use custom db.cache file" if 
there is a requirement to maintain DNS from a network 
that is isolated from the rest of the Internet.  
To turn off the use of the custom db.cache, just 
select:  "Use the standard db.cache file".