On 5/6/2011 6:40 AM, iharrathi....@orange-ftgroup.com wrote:
Thanks for the answer but:
*
In the example i post yesterday: on my server1 the recursion is
enabled (recursion yes), but the server1 can't recurse because i
stop it on firewall and it can't contact the outside.
*
You say "Don't use forwarding from a recursive server to a
non-recursive server" but when my server1 is recursive (and the
firewall allow it to contact the outside), and server2 don't
recurse because in it's conf recursion is set to no, when i ask
my server1 about ftp.example.com <ftp://ftp.example.com> (dig @0
ftp.example.com <ftp://ftp.example.com>) , server1 forward the
query to server2 which answer by the CNAME www.abc.com
<http://www.abc.com> and then server1 recurse to find the IP of
www.abc.com <http://www.abc.com>. and everything works fine.
*
you say "If server 2 is auth-only or otherwise can't resolve the
address of www.abc.com <http://www.abc.com/>, then forwarding a
query to it is not going to work." No as i say when server1
really recurse ( recursion yes, and the firewall allow the
server1 to contact outside) and server2 don't recurse (recursion
no) all is ok: server1 forward the query to server2 which answer
by the CNAME www.abc.com <http://www.abc.com/> and then server1
recurse to find the IP of www.abc.com <http://www.abc.com/>. and
everything works fine.
*
You say "then using a stub zone for example.com
<http://example.com/>will work", why i will use a stub zone
since a forward do the same thing expected.
And my question is always this:
forward only; as i read means a recursive query, in other term a query
with the RD bit is enabled. which means that when my server1 (which
has recursion yes but can't recurse because the firewall don't
allow it to contact the outside, which finally means server1 can't
recuse) ask server2 about ftp.example.com <ftp://ftp.example.com>,
server2 will normally make all the work means he read on it's zone,
then find the CNAME, then make a recursion to resolve the CNAME and
finally send the IP to server1.
why server2 don't recurse to find the IP of www.abc.com?
According to your own words: "server2 don't [sic] recurse because in
it's [sic] conf recursion is set to no". There's your answer.
Why are you dealing with such screwy configs anyway? If you need to
resolve things from the Internet, then you need to have a resolution
path to the Internet (either directly talking to Internet nameservers,
or some forwarding chain -- hopefully as short as possible, preferably
0-length -- to something that can query Internet nameservers directly).
If, on the other hand, you need to resolve something internal, then you
only need to have an authoritative source of that information
internally. Why are you complicating things more than they need to be?
Setting recursion and then blocking it via a firewall? What purpose does
that serve?
- Kevin
thanks for your help.
------------------------------------------------------------------------
*De :* Chris Buxton [mailto:chris.p.bux...@gmail.com]
*Envoyé :* jeudi 5 mai 2011 19:47
*À :* HARRATHI Issam Ext OLNC/DPS
*Cc :* bind-users@lists.isc.org
*Objet :* Re: forward first: iterative or recursive query
If recursion is disabled, forwarding doesn't happen. I think
you've confused some terms and configurations.
Don't use forwarding from a recursive server to a non-recursive
server. Use a stub zone instead, if you can't rely on the
recursion process to find the correct server to query.
If server 2 is auth-only or otherwise can't resolve the address of
www.abc.com <http://www.abc.com>, then forwarding a query to it is
not going to work. However, if server 1 is a caching server and is
able to resolve www.abc.com <http://www.abc.com>, then using a
stub zone for example.com <http://example.com> will work; server 2
will send the CNAME record to server 1, and then server 1 will
resolve the final address record on its own.
Chris Buxton
BlueCat Networks
On May 5, 2011, at 2:15 AM, <iharrathi....@orange-ftgroup.com
<mailto:iharrathi....@orange-ftgroup.com>>
<iharrathi....@orange-ftgroup.com
<mailto:iharrathi....@orange-ftgroup.com>> wrote:
Hi,
i have a server called server1 that is acting as a cache server(
recursion none). And i forward the zone example.com
<http://example.com> to server2 which has recursion enabled and
master on some zone like example.com <http://example.com>.
this is the forwarding zone on server1:
zone "example.com <http://example.com>" {
type forward;
forward only;
forwarders { IP_of server2; };
};
and server2 is master of the zone example.com <http://example.com>:
zone "example.com <http://example.com>" {
type master;
file "master/db.example.com";
};
BUT the problem is here:
db.example.com <http://db.example.com>:
....
$ORIGIN example.com <http://example.com>.
www A 1.2.3.4
ftp CNAME www.abc.com <http://www.abc.com/>
server1 can resolve www.example.com <http://www.example.com/>,
but can't resolve ftp.example.com <ftp://ftp.example.com> since
the server2 sends the answer which is www.abc.com
<http://www.abc.com/> and not the IP, and my server1 can't make
recursion to resolve www.abc.com <http://www.abc.com/>.
why?
from server1 when i dig on server2: dig @IP-server2
www.example.com <http://www.example.com/> it sends to me the IP,
all is OK!!! but with a forwarding statement it sends only the CNAME
server1 is bind9.6-ESV-R4 et server2 bind-9.4.2
Thanks.
Issam HARRATHI
------------------------------------------------------------------------
*De :* Chris Buxton [mailto:chris.p.bux...@gmail.com]
*Envoyé :* mercredi 4 mai 2011 08:49
*À :* HARRATHI Issam Ext OLNC/DPS
*Cc :* bind-users@lists.isc.org <mailto:bind-users@lists.isc.org>
*Objet :* Re: forward first: iterative or recursive query
With a static-stub zone, you would get an iterative query.
Forwarding always results in a recursive query.
How are you determining that your server is sending an
iterative query?
Can we (the list) see your named.conf?
Regards,
Chris Buxton
BlueCat Networks
On May 3, 2011, at 5:21 AM, <iharrathi....@orange-ftgroup.com
<mailto:iharrathi....@orange-ftgroup.com>>
<iharrathi....@orange-ftgroup.com
<mailto:iharrathi....@orange-ftgroup.com>> wrote:
Hi
from the book DNS and Bind 5th edition [french] (o'reilly)
I read that the forward with the mode first sends a
recursive query to the servers on the forwarders list, but
as i see it only sends an iterative query. Also with forward
only it send an itérative query.
So forward first send an itérative or recursive query?
And how i can send a recursive query with the statement
forward ( without using static-stub)
I'm using bind-9.6-ESV-R4
Thanks.
Issam HARRATHI.
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