we've had some curious behaviour on our internal lan now for a couple of
months. When a machine is turned on, it gets an ip from dhcp, it's dns
and default route. It can then ping any ip on the internal network, but
it can't ping any external ips despite having the correct routes. It
also can't use the dns service on its default gateway.
If I then ping our mail servers ip (which is an external ip, on a
different subnet) everything magically becomes ok. The said machine can
now connect to the internet just fine. This mail server is a different
machine from the gateway and firewall. It's nothing to do with the
routing of any internal machine, the only interesting feature i can
think of is that it's an external ip. But pinging other external ip
machines (on our network or beyond it) doesn't fix it like pinging this
The mail server, gateway and firewall are linux machines. The clients
can be linux or windows.
I'm not the sysadmin, but he can't think what it could be, and neither
can I. The firewall rules look fine to me, and there's no special rules
involving internal ips and that mail server ip.
Any suggestions? Or is it just the poltergeist again?
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