Shanker,
       I actually did not realize I could set it to ignore dhcp settings for 
dns from the client side.  I was trying to figure out how to get the VR to 
issue the dns settings I was interested in the guests having.
Thanks for that information,       David

From: shanker.ba...@shapeblue.com
To: users@cloudstack.apache.org
Subject: Re: Using different DNS for guests than Virtual Router
Date: Wed, 24 Apr 2013 04:31:20 +0000






On 23-Apr-2013, at 2:12 AM, David Ortiz <dpor...@outlook.com> wrote:



Hello,

   I am trying to setup a Windows AD server as a guest on my cloudstack 
cluster, and join my other guests to the domain it is serving using PowerBroker 
Identity Services Open.  From what I am seeing, the virtual router will block 
me from being able to perform
 nslookup or join the domain using the domainjoin-cli command.



David, I don't fully understand how the VR can block you from doing nslookups. 
While the VR does provide DNS services and I have not seen it prevent DHCP 
clients from using other DNS services (like 8.8.8.8) if a client is configured 
to use something else.


 If I modify /etc/resolv.conf to point directly at my DC as the dns server, it 
can join the domain without any issues.  Unfortunately when I reboot, the dhcp 
setup with the virtual router will point it back to the virtual router as the
 name server.



Yes, that's expected behaviour from DHCP clients. They will default to DHCP 
server supplied DNS information.



This default behaviour can be modified depending on your client OS. On Linux 
distros using "dhclient", look at dhclient.conf(5) man page for "supersede". 



       The supersede statement



        supersede [ option declaration ] ;



       If for some option the client should always  use  a  locally-configured

       value  or  values rather than whatever is supplied by the server, these

       values can be defined in the supersede statement.


I also found that I could get nslookup (but not joining the domain) to work by 
playing with the dnsmasq.conf settings on the virtual router a little bit, 
which works until it is rebooted at which point they revert back to what they 
had
 been originally.  Is there a way to get the virtual router to point guests at 
the domain controller as the DNS, or to set up the dnsmasq to allow the AD 
joins to occur (and make those settings persistent)?  Or alternatively, would I 
be able to set up DHCP
 on the DC and just circumvent the virtual router entirely?





The dhclient supersede option would fix the problem for you cleanly. The DHCP 
client will default to AD for DNS lookups and the join would succeed.



Hth.



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Shanker Balan

Managing Consultant





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