I rebooted a Fedora 25 server to find the network interface did not come up. Using the old “ifup eth0” returned an error.
/etc/resolv.conf "no such file or directory"
Huh? ls /etc/resolv.conf returns /etc/resolv.conf
It turns out NetworkManager replaces /etc/resolv.conf with a symbolic link to a NetworkManager directory.
Since NetworkManager is about as useful as lipstick on a pig with a server, it has to be removed. When you remove NetworkManager, it leaves /etc/resolv.conf as a dead symbolic link. Which, you don’t see without ls -lh /etc/resolv.conf.
When systemd’s init tries to bring up the interface without NetworkManager, there’s no /etc/resolv.conf there to write DNS information and therefore the interface never comes up.
TL;DR The three commands below fix it.
rm /etc/resolv.conf; ifdown eth0; ifup eth0;