Issue with Forwarding(URGENT!!!)

Lokesh Babu lokibabu at yahoo.com
Thu Jun 24 08:41:29 UTC 2004


After reading all the responses I tested the forwarding feature and
following are few observations with set-up:

In my set-up, I have RedHat 9.0 running BIND 9.2.3 (Machine 1)and two
other servers running BIND 9.2.3 and BIND 8.1.2.
Machine 1 is configured to forward the queries to the other two
servers in the order BIND 8.1.2 and BIND 9.2.3. In this case, I
observed that if the BIND 8.1.2 server has no data for a query (e.g. A
record), query is not going to BIND 9.2.3 machine. But, if I reverse
the order, i.e. BIND 9.2.3 is first in the forwarders list, query is
forwarded to 2nd server if the first server fails. So, it looks like
there is a compatibility issue between BIND 9.2.3 and BIND 8.1.2.
Please, let me know if it is(was) a known defect with BIND 8.1.2.
But, if I upgrade to BIND 8.2.X, there is no compatibility issue

Also from observation, it looks like forwarders are queried in the
listed order and not in any other order. I also went through the code
(query_find, query_recurse functions in query.c file). Even from this
code, it doesn't look like doing any intellingent thing like using
forwarders based on the response time. Please correct me if I am
wrong.

Thanks in advance,
Lokesh


Sten Carlsen <ccc2716 at vip.cybercity.dk> wrote in message news:<cba7cj$2jcq$1 at sf1.isc.org>...
> Joseph S D Yao wrote:
> >On Tue, Jun 22, 2004 at 12:21:45AM -0600, Sanjib Sanjib wrote:
> >  
> >
> >>Hi ,
> >>
> >>I have some problem in forwarding feature of bind 9.2 based DNS server.
> >>The configuration  done in my DNS server , which is BIND 9.2 is
> >>mentioned below 
> >>
> >>options{
> >>
> >>recursion true;
> >>allow-recursion {any;};
> >>forward first;
> >>forwarders {x.x.x.x; y.y.y.y;};
> >>}
> >>
> >>Details of server version in the forwarder list:
> >>x.x.x.x is Solaris (Bind 8.2) and y.y.y.y is( BIND 9.2) server.
> >>
> >>The problem is in query forwarding for some off site records . When
> >>ever you try to query any record which is not present in the
> >>authoritative data of my DNS server , it forwards to the DNS server in
> >>the forwarder list mentioned above. Now my problem is , whenever my 1st
> >>server(i.e. BIND 8.2) not able to respond the query for whatever reason
> >>, queries are not getting forwarded to the other server in the list .But
> >>if I reverse list in forwarder option is works fine for me. Is there any
> >>compatibility issue here???
> >>I just want to know how exactly it works in BIND 9.2 ? It works in
> >>round robin manner or from left to right ??
> >>Can any body suggest me , where is the problem ??? I am interested to
> >>know the implementation logic of forwarding in BIND 9.2. source code. 
> >>Since it's very urgent , I will appreciate your early response.
> >>Thanks in advance,
> >>Sanjib
> >>    
> >>
> >
> >Lists almost always mean to select ONE and ask it.  In fact, unless a
> >server completely fails to respond, I can't think of ANY lists in BIND
> >where servers are queried serially until you find the answer you like.
> >  
> >
> While it is not exactly BIND, the resolver (from ISC) does query all 
> available nameservers to find one that does answer (as far as I know) 
> the answer could then be that there is no answer. This might confuse 
> this discussion: the difference between
> no answer from server
> and
> the answer that there is no answer.
> 
> >Remember, that a "no answer available" answer is a valid answer.
> >Especially for a non-existent domain name.  Your server is forwarding
> >the query to the closest name server that is alive, and returning its
> >answer.  This is the correct operation for your configuration.
> >
> >  
> >


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