A customer’s freshly built guest RedHat 5 virtual machine (built from scratch, not cloned from a standard template) could not connect to the network, although all of the settings in the usual places seemed legit (/etc/sysconfig/network, /etc/sysconfig/network-scripts/ifcfg-eth0, /etc/resolv.conf). Pinging anything except for the local address resulted in “Destination host unreachable.”
After playing around with re-adding the vNIC, and trying the alternative e1000 driver, I finally came across a community post that seemed to indicate the virtualization options in the standard RHEL install don’t play nice as a guest OS configuration running on VMware. I had the customer look for processes having to do with KVM/Xen – he found that the Xen packages were installed and xend running. Uninstalling those packages and killing the Xen process restored networking immediately!