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From "Ivan X Yue" <>
Subject Re: AW:DNS in virtual router not stable
Date Thu, 13 Dec 2018 15:38:49 GMT
Hi, Ben,

Thanks for the reply.  We have been thinking about updating /etc/hosts of 
each of the VM to add the entries for other VMs.  Then we don't have 
dependency to the DNS in the virtual router.  But there's lots of work as 
VMs are being added / removed continuously in our case.  I just hope there 
will be easier solution.


From:   Benjamin Naber <>
To:     "" <>
Date:   2018/12/13 09:39 AM
Subject:        AW:DNS in virtual router not stable

Hi Ivan,

I've seen this problem to. The solution is to handle your ip address by 
the host youre adding static by api or gui. The router VM uses the old 
host entries set in /etc/hosts if you cleanup vpc network. The host file 
will be cleared.

Kind Regards


Von meinem Huawei-Mobiltelefon gesendet

-------- Originalnachricht --------
Betreff: DNS in virtual router not stable
Von: Ivan X Yue <>

Hi, all, 

We are using Cloudstack 4.9.2 with KVM and advance networking

We are having VPC network, and need to continuously adding / removing VM. 
One issue we found is, from time-to-time, on the VM deployed, it gets 
error that the hostname of the other VM is not resolved.  We dig into the 
VR, and it seems that every time a VM is added or removed, the dnsmasq 
needs to be restarted.  And based on /var/log/dnsmasq.log, there is 2 
second delay before dnsmasq is running again.  Quite likely while restart 
is happening, the DNS is not working and therefore VM will not be able to 
resolve hostname. 

Dec 12 15:22:55 dnsmasq[6479]: exiting on receipt of SIGTERM
Dec 12 15:22:57 dnsmasq[6747]: started, version 2.62 cachesize 150
Dec 12 15:26:36 dnsmasq[6747]: exiting on receipt of SIGTERM
Dec 12 15:26:38 dnsmasq[28921]: started, version 2.62 cachesize 150

We don't see this issue in CloudStack 4.11.  In 4.11, we also see dnsmasq 
being restarted in dnsmasq.log, but there is no delay between exiting and 

Is there anything we can do in 4.9.2 to have the DNS more stable.  e.g. 
can dnsmasq not being restarted even new VM info is added?  Or can it just 

reload the VM info?


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