Fedora Core 4 and weird DNS/nscd problems
I did a "yum update" to the latest glibc the other night. For some reason DNS was completely broken on my box today. There seemed to be a couple of problems: nscd wasn't being started; programs talking to nscd didn't seem to work, giving weird "file not found" errors.
I had a stale /etc/nsswitch.conf.rpmsave file left over, probably from the upgrade. I moved that to /etc/nsswitch.conf, did "chkconfig nscd on" and then "service nscd restart". Now DNS seems to work again.