How to set domainname permonently on RHEL?

[Zhou, Jingchen]

I know I can set it from the command line via "domainname my.domain", my question is how I can make it permanently (i.e., valid after reboot)?

Here is what I have:
- in /etc/hosts:
...
ip           xxx.my.domain xxx

- in /etc/resolv.conf
domain my.domain
search my.domain
....

- in /etc/sysconfig/network
HOSTNAME=xxx.my.domain

However, when I type "domainname", it returns "none", and when I type "hostname", it returns xxx.my.domain instead of xxx.

Am I missing any?

Thanks,
JC