Note that the 'host' command overrides some of the default resolv.h settings.
In particular the timeout is downgraded to a second, so if your internal server
is not working quick enough it will go to the secondary and return the failure.
What does ping on the host do? That will use a regular gethostbyname() with the
default resolv.h settings (eg: 5 second timeout).
What is the output of dig -t A <host> @10.10.10.4 say for the query time?
From: rhelv5-list-boun...@redhat.com
[mailto:rhelv5-list-boun...@redhat.com] On Behalf Of Gerhardus Geldenhuis
Sent: Thursday, March 01, 2012 9:00 AM
To: Red Hat Enterprise Linux 5 (Tikanga) discussion mailing-list
Subject: Re: [rhelv5-list] strange DNS resolution or lack off
Fair enough but then it should still be trying the first entry which it
apparently does not do which is basically my question.
resolv.conf man page is not very clear...
timeout:n
sets the amount of time the resolver will wait for
a response from a remote name server before retrying the query via a different
name server. Measured in seconds,
the default is RES_TIMEOUT (currently 5, see
<resolv.h>).
attempts:n
sets the number of times the resolver will
send a query to its name servers before giving up and returning an error to the
calling application. The default is
RES_DFLRETRY (currently 2, see <resolv.h>).
It fails to mention what a valid and invalid response would be and how
if/how it would be treated as a failure.
Regards
On 1 March 2012 15:43, Musayev, Ilya <imusa...@webmd.net> wrote:
Corey is correct. Record not found does not mean dns server is
unreachable, failover only occurs if dns server is unreachable on port 53.
From: rhelv5-list-boun...@redhat.com
[mailto:rhelv5-list-boun...@redhat.com] On Behalf Of Corey Kovacs
Sent: Thursday, March 01, 2012 10:23 AM
To: Red Hat Enterprise Linux 5 (Tikanga) discussion mailing-list
Subject: Re: [rhelv5-list] strange DNS resolution or lack off
They are tried in sequence if the first fails to talk to a
server at all, not if a record isn't found.
What you need is to have your internal DNS forward lookups to
the external DNS that are not handled by the internal.
C
On Mar 1, 2012 8:12 AM, "Gerhardus Geldenhuis"
<gerhardus.geldenh...@gmail.com> wrote:
Hi
I have a freshly build rhel5u7 server from the DVD not updated.
It has two interfaces:
DEVICE=eth0
ONBOOT=yes
HWADDR=00:0C:29:6B:78:6C
TYPE=Ethernet
BOOTPROTO=static
IPADDR=10.10.10.102
NETMASK=255.255.255.0
DNS1=10.10.10.4
DNS2=192.168.9.1
and
DEVICE=eth1
ONBOOT=yes
HWADDR=00:0C:29:6B:78:76
TYPE=Ethernet
BOOTPROTO=dhcp
DNS1=10.10.10.4
DNS2=192.168.9.1
PEERDNS=no
I have a custom /etc/resolv.conf
search example.com
nameserver 10.10.10.4
nameserver 192.168.9.1
If I run the command
host myserver.example.com I get
Host myserver.example.com not found: 3(NXDOMAIN)
However if I disable the second name server (192.168.9.1) it
works.
Now to explain the 10.10.10.4 server is my own dns server and
the 192.168.9.1 server is the dns server for all external dns lookups.
The docs says nameserver entries in /etc/resolv get tried
sequentially but it does not seem to happen for me.
I did a strace but I could not see anything significantly
different between the two lookups with different /etc/resolv.conf files.
I would appreciate anyone shedding any light on the problem.
ipv6 is disabled
Regards
--
Gerhardus Geldenhuis
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