The eth0 interface ; if it is working with out issues, It would be sufficient for Hadoop usage. Unless the test plan includes more than one network interface; such as network performance Hadoop testing , in this case, I recommend share mode bonding interface for the best network bandwidth. Here is more info about the different bonding interfaces. thttp://wiki.centos.org/TipsAndTricks/BondingInterfaces
Please use FQDN.