virtualbox.org

Hello,

I am trying to create a 2-node Oracle 12c RAC using VirtualBox 5.1.4. Version Oracle 12c Grid Infrastructure (GI) requires DNS. I have been trying to use dnsmasq (for DNS) and I have it working sucessfully to a degree. My two guest nodes (rac01 and rac02) are running CentOS7 with two Internal Network adaptors. My dnsmasq guest server is running CentOS7.

• My dnsmasq guest server can both ping and do nslookups of guest systems (rac01 and rac02) no problem.
• My two guest systems (rac01 and rac02) can ping each other and the dnsmasq dns server but cannot perform nslookups.

What can you recommend?

What could be blocking nslookups in a VirtualBox environment?


Thanks,

Michael

I'm not sure if this applies to your case, but the release notes for the 5.1.7 TestBuilds, contain the following:

• NAT Network: when the host has only loopback nameserver that cannot be mapped to the guests (e.g. dnsmasq running on 127.0.1.1), make DHCP supply NAT Network DNS proxy as nameserver.

The terminology is a little too esoteric for me, so I'll let you do the testing
https://www.virtualbox.org/wiki/Testbuilds

Thanks for posting that. After I read it 5 times to get near understanding it, I am not using DHCP. All my VM's are using static IPs. They are all set to "Internal Network" and on that network I have also created a dns server via dnsmasq.

I was thinking maybe I need to tell VirtualBox to use my internal guest VM to be a DNS somewhere as even though it is on the same network it is not finding it. All the VM guests on that network can ping each other. Again, nslookup is working (resolving the hostnames) on my dnsmasq dns server ONLY but not from my other VM CentOS7 guests (even though the resolv.conf is set on the guest to use my dnsmasq guest as the dns).

What can you recommend?

Thanks,

Michael

By definition if you can reach the guests from each other then VBox has done its thing. Everything else will be a configuration/use issue. I suspect you have not defined the guests friendly names or added them to the DNS server. Not sure how you do that with dnsmasq but you should be able to find out how. I normally just use a real DNS server and be done with it.

dnsmasq and nslooks ARE working. It was my misunderstanding of how dnsmasq works that was wrong. dnsmasq needs to be installed on every system that needs DNS emulated. I was so fixed on dnsmasq working like a remote DNS server I did not see the obvious.

Thanks for all your comments which ultimately pointed me in the direction of seeing how dnsmasq actually works.

-Michael

Thanks for letting us know.