A question regarding the db.cache file

[Klas Bengtsson]

Hi again!

Another question in the same area:

What if I instead of using the db.cache file list my name servers as 
forwarders in the named.conf file. That means having my DNS server 
configured as a forwarding-only DNS server (recursive mode). Let's say that 
I have two DNS servers listed in the forwarders statement in the named.conf 
file.

How does this algorithm work? Does it work the same way as when I had my 
name servers in the db.cache file? Will named still query booth DNS servers 
initially and find out the RTT, and then use the one with the lowest RTT as 
primary?

And finally the same question as I asked in my first mail:

"If one server becomes unreachable, then the other one is selected. But what 
triggers the coming back into play of the first server (once the fault is 
removed)?"

Is the answer the same in this case, that is will the same backup algorithm 
be used for the old response time numbers? Or do we at all deal with RTT 
values in this case?

BR,
Klas


>From: Brad Knowles <brad at stop.mail-abuse.org>
>To: "Klas Bengtsson" <klasbengtsson99 at hotmail.com>
>CC: brad at stop.mail-abuse.org, bind-users at isc.org
>Subject: Re: A question regarding the db.cache file
>Date: Wed, 13 Jul 2005 18:45:48 +0200
>
>At 4:07 PM +0200 2005-07-13, Klas Bengtsson wrote:
>
> >  Thanks for your answer. Do you happen to know with what amount the RTT
> >  is slowly reduced?
>
>	It's an exponential backoff algorithm, but I don't recall the
>specifics.  More detail can surely be had in the RFCs and the book
>_DNS and BIND_ by Paul Albitz and Cricket Liu.
>
>--
>Brad Knowles, <brad at stop.mail-abuse.org>
>
>"Those who would give up essential Liberty, to purchase a little
>temporary Safety, deserve neither Liberty nor Safety."
>
>      -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
>      Assembly to the Governor, November 11, 1755
>
>    SAGE member since 1995.  See <http://www.sage.org/> for more info.
>
>

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