[CentOS] Slow CentOS VM when running off the network

Renato de Oliveira Diogo renato.diogo at gmail.com
Tue Jun 16 19:20:23 UTC 2009

Brian is correct...

check the /etc/hosts if your hostname and hostname.hostdomain is
registred here. Eg. if a MTA (sendmail) don´t resolv the hostname of
the host is gerated a big delay. Put the hostname in loopbak interface

And is not in VM, in physical host the same "problem"

Renato de Oliveira Diogo

Bacharel em Ciência da Computação
UNESP - Bauru

LPIC1 - Linux Professional Institute Certification - Nível 1

renato.diogo at gmail.com
renato.diogo at yahoo.com.br

On Tue, Jun 16, 2009 at 16:03, Brian Mathis<brian.mathis at gmail.com> wrote:
> 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.
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