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From Santhosh Edukulla <santhosh.eduku...@citrix.com>
Subject RE: DNS service on VR not responding
Date Sun, 20 Jul 2014 17:17:35 GMT
Run trace route from guest vms, the result will yield to the point where packet drop is happening,
could be a network acl rule issue, but tracert command can lead to some answers.

List running ports as well on VR, do a telnet to dns port on router from guest vm to verify
for its response.

Santhosh
________________________________________
From: Indra Pramana [indra@sg.or.id]
Sent: Sunday, July 20, 2014 1:06 PM
To: users@cloudstack.apache.org
Cc: dev@cloudstack.apache.org
Subject: Re: DNS service on VR not responding

Hi Rafael,

Good day to you, and thank you for your reply.

Can't find anything wrong on dnsmasq.log / daemon.log, just some log
entries related to DHCP, nothing on DNS. I masked the IP addresses since
they are public.

===
Jul 20 16:21:51 r-2606-VM dnsmasq[3519]: DHCPDISCOVER(eth0) X.X.X.X
06:62:a8:01:13:37
Jul 20 16:21:51 r-2606-VM dnsmasq[3519]: DHCPOFFER(eth0) X.X.X.X
06:62:a8:01:13:37
Jul 20 16:21:51 r-2606-VM dnsmasq[3519]: DHCPREQUEST(eth0) X.X.X.X
06:62:a8:01:13:37
Jul 20 16:21:51 r-2606-VM dnsmasq[3519]: DHCPACK(eth0) X.X.X.X
06:62:a8:01:13:37 yyyyyy
Jul 20 16:23:53 r-2606-VM dnsmasq[3519]: DHCPINFORM(eth0) X.X.X.X
06:43:4a:01:12:65
Jul 20 16:23:53 r-2606-VM dnsmasq[3519]: DHCPACK(eth0) X.X.X.X
06:43:4a:01:12:65 zzzzzz
===

Yes, the guest VMs are having difficulties resolving domains into IP
addresses because of the problem on the VR's DNS server.

$ host www.google.com X.X.X.X (where X.X.X.X is the IP address of the VR)
;; connection timed out; no servers could be reached

However, from within the VR, I am able to resolve domains just fine.

Any advise where can I start troubleshooting this?

Looking forward to your reply, thank you.

Cheers.



On Sun, Jul 20, 2014 at 11:26 PM, Rafael Weingartner <
rafaelweingartner@gmail.com> wrote:

> Have you taken a look at dnsmasq.log in the VR ?
> What do you mean with not responding? The addresses are not being resolved
> to ip addresses?
>
>
> On Sun, Jul 20, 2014 at 11:53 AM, Indra Pramana <indra@sg.or.id> wrote:
>
> > Dear all,
> >
> > All our guest VMs are having our virtual router (VR)'s IP address on
> > /etc/resolv.conf. In the past two weeks, I just realised that the DNS
> > service on the VR is not working, and doesn't respond to DNS queries from
> > the DNS clients on the guest VM.
> >
> > I have tried to stop and start back the VR, but the problem persists.
> >
> > DHCP services seems to be running fine, only DNS services are not
> working.
> > From what I understand, both services are provided by dnsmasq, correct?
> >
> > Any advice on how can I resolve the problem?
> >
> > Looking forward to your reply, thank you.
> >
> > Cheers.
> >
>
>
>
> --
> Rafael Weingärtner
>

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