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
I don't think it ever sends queries spontaneously. It uses the RTT of the
forwarded queries.
I think that the way that it discovers when 10.10.10.10 has come back is by
"penalizing" 192.168.1.1 each time it uses it. Eventually the penalty gets
large enough that it will try another server in its list for the domain.
This is the same for both "type forward" zones and domains known via NS
records.
--
Barry Margolin, bar...@genuity.net
Genuity, Woburn, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.
BIND doesn't send SOA queries to compute RTT values. It only
queries the forwarders when it has a recursive query to reply
to and updates RTT based on the responses.
Also, note that tracking RTT for forwarders doesn't work
correctly in BIND 8 until 8.2.3, and isn't supported in BIND 9
at all.
cricket
Men & Mice
DNS Software & Services
www.menandmice.com
Attend our next DNS and BIND class! See
http://www.menandmice.com/8000/8000_dns_training.html
for the schedule and to register for upcoming classes
Thanks. How does BIND 9 do it?
>
> cricket
>
> Men & Mice
> DNS Software & Services
> www.menandmice.com
>
> Attend our next DNS and BIND class! See
> http://www.menandmice.com/8000/8000_dns_training.html
> for the schedule and to register for upcoming classes
--
Anthony
BIND 9 name servers query the forwarders in the order in which
they're listed, just like BIND 8 did before 8.2.
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
--
Anthony
As long as it's up.
Sure, I'm interested.
Hmm. I've been reading the code and it looks like you're right
about the timeouts. In BIND 9, the timeout when querying a
forwarder seems to be no different than the timeout when querying
any other name server. In fctx_setretryinterval(), the retry timeout
is two seconds for the first two tries, as long as the name server's
RTT isn't larger than two seconds. If it is, the retry is the RTT.
Oh, and the retry is always trimmed to 30 seconds.
However, Bob's comment in fctx_getaddresses() certainly suggests
that the forwarders are queried in a fixed order:
* XXXRTH We could sort the forwaddrs here if the caller
* wants to use the forwaddrs in "best order" as
* opposed to "fixed order".
*/
And, sure enough, sort_finds() sorts fctx->finds rather than
fctx->forwaddrs, which I believe means it's only sorting the list
of name servers we've found in our local database while doing
iterative name resolution, not the forwarders.
I'm copying bind9-users on this, since most of the BIND 9
developers hang out there. They can give us the authoritative
answer.
Sure it does.
> In cache dump of a Bind 8 server, the rtt "of the moment" was in comments
in the
> A-record of the name server, but the cache dump of a Bind 9 server show
nothing
> there. Which makes me wonder.
My guess is that they simply changed the format of the dump file.
cricket
Men & Mice
DNS Software, Training and Consulting
Mark
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: Mark.A...@isc.org