name server on esx server and ms dns slow recursion

Michael P. Varre mvarre at
Wed Jul 16 19:52:33 UTC 2008

> -----Original Message-----
> From: ubuntu-users-bounces at [mailto:ubuntu-users-
> bounces at] On Behalf Of chris
> Sent: Wednesday, July 16, 2008 12:26 PM
> To: Ubuntu user technical support, not for general discussions
> Subject: name server on esx server and ms dns slow recursion
> I have a very complex issue and I'm needing some help.
> Due to the DNS poison cache thing, we need to update our 4 dns
> servers. They are currently on SLES 10 and 9. 3 are VMs in ESX
> environment. 1 is a physical box (ns1).
> Our subscription to Novell has expired and we figured why not tech
> refresh to Ubuntu and save the $$. So I built a Ubuntu x64_86 VM on
> our dev environment. It worked great.
> I migrated it out over time to become NS2, 3, 4. I then switched the
> physical box off and made it a VM as well. I was told that they had
> originally had NS1 as a VM but had issues with having slow recursion
> lookups. So they moved it to physical and it was fine then. NS1 being
> the master obviously. Anyway... didn't seem to have that issue here
> with Ubuntu.
> About 2 hours later after the bring up of the new VMs, we started to
> get user complaints of 'slow internet'. Digging into it, looked like
> DNS was slow to resolve.
> The way our network works, is the following.
> Users will send query to a local Microsoft DNS server which will
> forward to the root MS DNS server for the domain which will forward to
> the Ubuntu boxen. The forward between the MS root servers and the
> Ubuntu boxen was where it was slow. Queries taking 2-4 seconds to
> return.
> If we took users and pointed to the Ubuntu boxes themselves, they were
> fine.
> I backed out and shut down all my VMs and brought the physical NS1 and
> the old VMs back online and the users were happy.
> I honestly can't see this being an Ubuntu issue or a VM issue. But I
> suspect something with the 9.4.2-P1 version of bind and MS DNS. We're
> only doing around 300 queries/sec. No where near the 10k saying that
> there are issues on isc's site.
> I've Googled around and not gotten much back. I'm hoping someone may
> have some ideas as to what is the cause or if someone has seen this
> before b/c I feel like I'm loosing my mind.
> Thanks in advance.
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[Michael P. Varre] 

I've been running bind9 on fbsd 6.2 on ESX3 for a couple years now with no
performance issues.  For the last couple weeks I've been running on ESX3.5,
bind (now BIND 9.4.2-P1) on ubuntu 8.04 LTS doing full recursion for my
internal servers, mail servers, DNSBL and mail filters with no
problems....quite the contrary actually.  I don't have hard numbers but it
seems to fly in its current state.

My Ubuntu setup is as vanilla as possible.  Hope this helps at least take
the finger away from vmware, esx, or Ubuntu a bit.

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