The default install of Red Hat Enterprise Linux 6 (RHEL6 and CentOS6) automatically includes the NetworkManager service which was optional in previous versions. The purpose for NetworkManager is to make RHEL6 more portable which is great for a notebook computer or perhaps a desktop. Portability is not a major concern for a server. Usually servers are fairly fixed and configuration of network settings is done statically using manual tools. NetworkManager also does not support many advanced networking features like IP forwarding. Read more