hostname configuration in centos

Question : which file contains hostname in  Linux   ?

Question : how to configure host name in centos ?

Question : how to change hostname in linux ?

Step A

Change hostname temporary

# hostname < your hostname >

# hostname  linuxtopic.com

After the system

Step B

Change hostname permanently 

#Vi  /etc/sysconfig/network

#format

NETWORKING =yes

HOSTNAME=lokesh