1. Two or more NICs in the server.
2. All cards are set-up with the same configuration and ARE ALL UP.
3. The cable is plug into ONLY ONE card AND NOT ETH0.
The result is, although the settings are all correct but the default path defined in the system is via eth0. Well, that’s very annoying and time-wasting.
Just take a note for me to comment (or down) unused card settings in the future.