On a system with both a modem and network card configured by dhcp: Normally you set your DNS settings in "netconf", however, in a system with both a modem and a Network Interface Card configured by DHCP, your DNS settings will be overwritten on each boot with the alleged "gateway" address, whether or not it provides accurate DNS service. (Ours certainly doesn't =) If you fiddle with the settings enough (ie, removing the default domain, or changing the priority of DNS on the same screen) your system will never, ever boot again. (Hangs at 'initializing eth0', in my test, for well over a day before I rebooted it.) I don't know which actual service is causing the problem, though obviously it's something to do with the nic routines or dhcp configuration utility. To avoid hearing "update the driver", or something equally inspired, I should mention that we have tested this on multiple computers, nics, and modems, and have found the problem universal. It is also worth note that, upon installing 6.0 on those computers, there is no longer any problem. As our distributor can no longer acquire RedHat 6.0 retail, this is not a viable option for customers who want the full documentation with the product. This seems to be a high priority item, as a lot of systems do go out the door with both devices... P.S. While normally I'd like to just submit a bug report, instead of blaming it on a specific component, (and then being wrong), bugzilla doesn't seem much inclined to allow me to do so. So if pump isn't at fault, I have no idea what is.
This seems to be a very special case that may just require a manual hack on the sysadmin's part. If I gather correctly, the problem is that dhcpd is writing the resolv.conf twice and the final result is the one from the modem rather than eth0? It is somewhat confusing because you refer to both DNS (name resolution settings) and the gateway (routing settings). (I've never seen DHCP over a serial modem - PPP has its own settings negotiation protocol.)
No reply, not a surprise after all this time.