[CentOS] Slow CentOS VM when running off the network

[Brian Mathis]

On Tue, Jun 16, 2009 at 1:50 PM, Alfred von Campe<alfred at von-campe.com> wrote:
> I have a CentOS 5.3 VM running under VMware on a WIndows XP laptop.
> Everything works fine when connected to the network.  However,
> removed from the network, most everything in the CentOS VM takes
> minutes to complete.  For instance, starting a new Terminal window
> takes over 3 minutes.  I did an strace, and there are a couple of
> long waits when trying to open a socket (/tmp/.ICE-unix/XXXXX for
> instance).
>
> The host and the VM can ping each other fine, but any access to the
> VM (either external or from within) eventually succeeds, but it takes
> a long time.  First, I thought I'd reduce the default socket timeout
> (which I believe is set to around 90 seconds), but I can't find where
> to do that on a system wide level.  But I really need to figure out
> what is causing the problem in the first place.  I'm assuming the
> network is somehow misconfigured, but I don't know how.
>
> Alfred

This is a classic sign of DNS query timeouts.  When you are connected
to the network the system is making DNS queries which respond quickly.
 When you are not connected, the host makes DNS queries and waits for
a response.  The timeout is a minute or so, so you will see a long
delay in any program that tries to resolve DNS.  Many programs use DNS
even if it's not entirely obvious why.

You didn't say which virtual network this machine is connected to, but
you probably want to use the NAT network and allow the VM to receive
the DNS server configuration via DHCP.