Allow Linux box in intranet to access internet via a gateway server

I have three servers in a intranet environment. One(A) can access internet directly. Others(B andC) are connected to A.

In order to allow B and C access internet, do the following settings:
1. vi /etc/resolve.conf
Add the following text in it:

nameserver <a's IP>

2. vi /etc/sysconfig/network
Add

GATEWAY= <a's IP>

3. Run /etc/init.d/network restart

Do the three steps on both B and C. Then they should both be able to access internet.
Try it by ping yahoo.com.