On RHEL and similar distributions such as CentOS and OEL you can set the hostname by adding a hostname entry in /etc/sysconfig/network.
If you don't have such an entry, the system will fall back to the default behaviour - referencing the hostname configured on the first matching entry in /etc/hosts.
192.168.92.101 hydrogen.lan hydrogen
Now, my question is. Are there any good reasons to use the direct hostname configuration in /etc/sysconfig/network or is it simply redundant in most scenarios?