does type forward zones make BIND 8 continuously poll?

[Marc Thach Xuan Ky]

Anthony,
BIND doesn't use SOA for RTT, it just measures RTT for queries sent, no
polls.  If there are no queries, there's no RTT calculation.  When
10.10.10.10 first goes down, then your BIND will send to 10.10.10.10 first.
After no response four seconds later it will try 192.168.1.1.  Assume it
gets a response then.  It will multiply the stored RTT for 10.10.10.10 by a
constant 1.2 because it had no response, and decrement the RTT for he
now-working 192.168.1.1 using the formula 0.7*Old_RTT + 0.3*New_RTT.  It may
take a few queries before 192.168.1.1 is tried first.  Even then,
occasionally 10.10.10.10 will be retried.  This is BIND 8.2.3 and higher,
BIND 9 is different, it doesn't use the RTT method at all for forwarders.
Hopefully they'll put it back at some stage.
Marc TXK

Anthony Golia wrote:

> I mean if I do this:
>
> zone "foo.com" {
>         type forward;
>         forward only;
>         forwarders {
>                 10.10.10.10;
>                 192.168.1.1;
>         };
> };
>
> and things happen in this order:
>
> -       192.168.1.1 is down
> -       BIND comes up, requests for foo.com come in, BIND frwrds them to
> 10.10.10.10
> -       10.10.10.10 goes down, 192.168.1.1 comes up, requests come in
>
> how often does BIND send SOA queies for it's RTT calcs?  any help is
> appreciated.
>
> --
> Anthony