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From Indra Pramana <in...@sg.or.id>
Subject Re: DNS service on VR not responding
Date Mon, 21 Jul 2014 09:56:32 GMT
Hi Vihar,

Are you referring to /etc/resolv.conf on the VR itself or on the guest VM?

On the VR itself, there are only two entries on /etc/resolv.conf pointing
to both Google public DNS servers.

On the guest VM, there are 3 entries, one to the VR and two to the Google
public DNS servers. If I commented out both Google DNS servers and only
leaving the VR IP there, I cannot resolve anything. If the VR IP is
commented out and leaving both Google DNS servers there, then I can
resolve. So the issue is confirmed due to DNS service on the VR.

But I am not too sure why it doesn't respond even though the dnsmasq
service is running.

Thank you.






On Mon, Jul 21, 2014 at 1:00 PM, Vihar <vih1310@gmail.com> wrote:

> Hi ,
>
> I would like you to comment second and third IP address I.e 4.2.2.2 and
> 8.8.8.8 and uncomment the first IP which is allocated to DNS and try to
> resolve the internet. It might be resolving the queries from external DNS
> server.
>
> If you are not able to resolve the names from VR, check if the DNS service
> is running properly for the IP which act as a DNS server.
>
> Regards
> Vihar
> On Jul 21, 2014 10:19 AM, "Indra Pramana" <indra@sg.or.id> wrote:
>
> > Hi Sanjeev,
> >
> > Good day to you, and thank you for your reply.
> >
> > Yes, I can resolve domains without any issues from within the VR itself.
> >
> > root@r-2606-VM:/etc# ping yahoo.com
> > PING yahoo.com (98.139.183.24): 56 data bytes
> > 64 bytes from 98.139.183.24: icmp_seq=0 ttl=47 time=250.473 ms
> > 64 bytes from 98.139.183.24: icmp_seq=1 ttl=47 time=239.240 ms
> > 64 bytes from 98.139.183.24: icmp_seq=2 ttl=45 time=247.605 ms
> > 64 bytes from 98.139.183.24: icmp_seq=3 ttl=45 time=244.913 ms
> > ^C--- yahoo.com ping statistics ---
> > 4 packets transmitted, 4 packets received, 0% packet loss
> > round-trip min/avg/max/stddev = 239.240/245.558/250.473/4.144 ms
> >
> > root@r-2606-VM:/etc# ping google.com
> > PING google.com (74.125.68.102): 56 data bytes
> > 64 bytes from 74.125.68.102: icmp_seq=0 ttl=52 time=1.353 ms
> > 64 bytes from 74.125.68.102: icmp_seq=1 ttl=52 time=1.199 ms
> > 64 bytes from 74.125.68.102: icmp_seq=2 ttl=52 time=1.268 ms
> > 64 bytes from 74.125.68.102: icmp_seq=3 ttl=52 time=1.287 ms
> > ^C--- google.com ping statistics ---
> > 4 packets transmitted, 4 packets received, 0% packet loss
> > round-trip min/avg/max/stddev = 1.199/1.277/1.353/0.055 ms
> >
> > The VR uses 8.8.8.8 and 8.8.4.4 to resolve domains.
> >
> > root@r-2606-VM:/etc# cat /etc/resolv.conf
> > nameserver 8.8.8.8
> > nameserver 8.8.4.4
> >
> > I can ping both name servers without any issues.
> >
> > root@r-2606-VM:/etc# ping 8.8.8.8
> > PING 8.8.8.8 (8.8.8.8): 56 data bytes
> > 64 bytes from 8.8.8.8: icmp_seq=0 ttl=52 time=4.693 ms
> > 64 bytes from 8.8.8.8: icmp_seq=1 ttl=52 time=2.390 ms
> > 64 bytes from 8.8.8.8: icmp_seq=2 ttl=52 time=2.523 ms
> > 64 bytes from 8.8.8.8: icmp_seq=3 ttl=52 time=2.458 ms
> > ^C--- 8.8.8.8 ping statistics ---
> > 4 packets transmitted, 4 packets received, 0% packet loss
> > round-trip min/avg/max/stddev = 2.390/3.016/4.693/0.969 ms
> >
> > root@r-2606-VM:/etc# ping 8.8.4.4
> > PING 8.8.4.4 (8.8.4.4): 56 data bytes
> > 64 bytes from 8.8.4.4: icmp_seq=0 ttl=52 time=2.649 ms
> > 64 bytes from 8.8.4.4: icmp_seq=1 ttl=52 time=2.458 ms
> > 64 bytes from 8.8.4.4: icmp_seq=2 ttl=52 time=2.436 ms
> > 64 bytes from 8.8.4.4: icmp_seq=3 ttl=52 time=2.393 ms
> > ^C--- 8.8.4.4 ping statistics ---
> > 4 packets transmitted, 4 packets received, 0% packet loss
> > round-trip min/avg/max/stddev = 2.393/2.484/2.649/0.098 ms
> >
> > Looking forward to your reply, thank you.
> >
> > Cheers.
> >
> >
> >
> >
> > On Mon, Jul 21, 2014 at 12:18 PM, Sanjeev Neelarapu <
> > sanjeev.neelarapu@citrix.com> wrote:
> >
> > > Hi,
> > >
> > > Can you check if the VR is able to resolve the domain names by pinging
> > > from VR ?
> > >
> > > -Sanjeev
> > >
> > > -----Original Message-----
> > > From: Vihar [mailto:vih1310@gmail.com]
> > > Sent: Monday, July 21, 2014 5:43 AM
> > > To: users@cloudstack.apache.org
> > > Cc: dev@cloudstack.apache.org
> > > Subject: RE: DNS service on VR not responding
> > >
> > > Hi,
> > >
> > > Yes, if I remove or comment out the first nameserver entry for the VR's
> > > IP, and only leaving 8.8.8.8 and 8.8.4.4, guest VMs will be running
> fine
> > > and will be able to resolve domains properly."
> > >
> > > Are you able to ping the first DNS server IP address that you commented
> > > out?
> > >
> > > Regards
> > > Vihar K
> > >  On Jul 20, 2014 11:29 PM, "Santhosh Edukulla" <
> > > santhosh.edukulla@citrix.com>
> > > wrote:
> > >
> > > > Do a traceroute to an external domain say google.com from guest vm,
> as
> > > > you mentioned below, both by commenting out vr ip and not, in
> > > > resolv.conf, you may see the difference.
> > > >
> > > > "Yes, if I remove or comment out the first nameserver entry for the
> > > > VR's IP, and only leaving 8.8.8.8 and 8.8.4.4, guest VMs will be
> > > > running fine and will be able to resolve domains properly."
> > > >
> > > >
> > > > Santhosh
> > > > ________________________________________
> > > > From: Indra Pramana [indra@sg.or.id]
> > > > Sent: Sunday, July 20, 2014 1:48 PM
> > > > To: users@cloudstack.apache.org
> > > > Cc: dev@cloudstack.apache.org
> > > > Subject: Re: DNS service on VR not responding
> > > >
> > > > Hi Santhosh,
> > > >
> > > > Good day to you, and thank you for your email.
> > > >
> > > > Traceroute packets seems to be dropped, I think it's by default. See
> > > > result
> > > > below:
> > > >
> > > > # traceroute X.X.X.2
> > > > traceroute to X.X.X.2 (X.X.X.2), 30 hops max, 60 byte packets
> > > >  1  * * *
> > > >  2  * * *
> > > >  3  * * *
> > > >
> > > > However, I am able to ping, and there is a response when I tried to
> > > > telnet to port 53.
> > > >
> > > > 64 bytes from X.X.X.2: icmp_req=4 ttl=64 time=2.00 ms
> > > > 64 bytes from X.X.X.2: icmp_req=5 ttl=64 time=0.291 ms
> > > > 64 bytes from X.X.X.2: icmp_req=6 ttl=64 time=0.384 ms ^C
> > > > --- X.X.X.2 ping statistics ---
> > > > 6 packets transmitted, 6 received, 0% packet loss, time 4999ms rtt
> > > > min/avg/max/mdev = 0.270/0.603/2.006/0.628 ms
> > > >
> > > > # telnet X.X.X.2 53
> > > > Trying X.X.X.2...
> > > > Connected to X.X.X.2.
> > > > Escape character is '^]'.
> > > >
> > > > netstat -a on the VR shows the service is listening on domain port
> > (53).
> > > >
> > > > tcp        0      0 r-2606-VM:domain        *:*
> > > LISTEN
> > > >
> > > > tcp        0      0 X.X.X.2:domain     *:*                     LISTEN
> > > >
> > > > udp   156992      0 r-2606-VM:domain        *:*
> > > >
> > > > udp   164032      0 X.X.X.2:domain     *:*
> > > >
> > > > Can you advise if there's anything else I need to check?
> > > >
> > > > Looking forward to your reply, thank you.
> > > >
> > > > Cheers.
> > > >
> > > >
> > > >
> > > >
> > > > On Mon, Jul 21, 2014 at 1:17 AM, Santhosh Edukulla <
> > > > santhosh.edukulla@citrix.com> wrote:
> > > >
> > > > > 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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