netmask: Host name lookup failure

[Wahyu Darmawan]

Hi,
Need some help.
I've Red Hat Linux AS 2.1. There is two LAN cards (eth0 and eth1), and I've added new one just now (eth2).
All devices has been detect, but when I configured eth2 with new IP, and I ran command 'ifup eth2', appeared error message :

netmask: Host name lookup failure

And once more after that, my eth1 couldn't ping by outside. Can you help me?

Many thanks before...