no servers could be reached
Kevin Darcy
kcd at chrysler.com
Mon Oct 20 21:25:15 UTC 2008
info at mtdatasure.com wrote:
> I have bind 9.3.4 install and running on RH5. I am not able to query it successfully. Here are the trouble shooting techniques I have used thus far: All of them work when run from the command line of the DNS server its self. The trouble starts when trying to query this DNS server from another machine. So again, locally, DNS queries are working.
>
> Explicitly using TCP, a query is successful
> dig @xx.xx.xx.xxx yahoo.com. soa +vc
>
>
> When using UDP (as I assume the following command does) no luck. The following is printed.
> dig @xx.xx.xx.xxx yahoo.com.
>
> ; <<>> DiG 9.2.4 <<>> @xx.xx.xx.xxx yahoo.com.
> ; (1 server found)
> ;; global options: printcmd
> ;; connection timed out; no servers could be reached
>
> I have also tried:
> nslookup
>
>> lserver xx.xx.xx.xxx
>> www.abcnews.com
>>
>
> I recieve the same message, connection timed out: no servers could be reached.
>
> I am able to telnet into port 53, as I'm sure the TCP port is working just fine.
>
> The lsof command shows the following:
>
> named 3776 named 20u IPv4 12822 UDP 127.0.0.1:domain
> named 3776 named 21u IPv4 12823 TCP 127.0.0.1:domain (LISTEN)
> named 3776 named 22u IPv4 12824 UDP xx.xx.xx.xxx:domain
> named 3776 named 23u IPv4 12825 TCP xx.xx.xx.xxx:domain (LISTEN)
> named 3776 named 24u IPv4 12826 UDP *:40624
> named 3776 named 25u IPv6 12827 UDP *:48884
> named 3776 named 26u IPv4 12828 TCP 127.0.0.1:rndc (LISTEN)
>
> And finally, I have tried these commands with the firewall turned off. It appears as if UDP port 53 simply isn't listening. I am out of ideas.
>
Hopefully you understand that UDP sockets aren't "listened" in the same
way that TCP sockets are. On the Solaris man page for listen(3SOCKET),
for instance, the text says "The listen() call applies only to sockets
of type SOCK_STREAM or SOCK_SEQPACKET." UDP sockets are of type
SOCK_DGRAM. I wouldn't consider the above display abnormal, then,
although you might want to compare to a known working system.
How exactly have you configured your BIND to resolve Internet names? By
forwarding to your ISP's nameservers? Or with an Internet root hints
file, where everything else is fetched via iterative resolution?
If you're forwarding, then try generating some queries to your
forwarders and see what you get.
If you're resolving iteratively, try dig +trace or mimicking the
iterative resolution process manually by starting at the root zone and
following the referrals on down.
- Kevin
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