Maintain task frequency

/dev/rob0 rob0 at
Tue May 10 00:34:40 UTC 2016

On Mon, May 09, 2016 at 05:54:22PM -0500,
   Jorge Alberto Martínez Melo wrote:
> I am preparing some scripts to maintain some cache dns servers and 
> I am thinking about the most appropriate frequency of these tasks:
> - to generate the root hints file (root cache).

Never.  You'll get new root hints every time you upgrade, if the 
hints have in fact changed.  Even if you don't upgrade, it doesn't 
matter.  Having a wrong address in hints means that you might try 
contacting a bad IP address at startup.

Once you have found an actual root server you'll never go back to the 
hints.  And you can find actual root servers listed in hints files 
which date back far before the BIND 9 project's existence.

For ease of management you might want to remove the "zone '.'" 
statements from your recursive resolvers.  That way you'll only use 
the built-in hints, and every time you upgrade, such as for the 
latest security issue, you've got the new hints.

There's a recent article at the ISC KB about root hints, you might 
want to read that also.  It should be easy to find at , searching for "root hints".

> - to clear the cache with rndc flush

Oh my!  Never, unless you have some good reason to do it.  Why do you 
think that should be a scheduled task?

> - to generate the stats file with rndc stat

Never.  See the statistics-channels functionality, which is far 
superior to the "rndc stats" output, in real time as needed, and 
designed to be easily parsed by automated tools.
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