Setting Hostname in Redhat Linux

1. Check which DHCP client are you using dhcpcd , dhclient and pump
2. Remove /etc/resolv.conf file and touch a new /etc/resolv.conf Or do a cp /dev/null etc/resolv.conf
3. Add an entry into /etc/sysconfig/network such that it looks as follows
4. NETWORKING=yes
   HOSTNAME=bacan01-l-t1
   DHCP_HOSTNAME=REDHAT
   
   where REDHAT is the new hostname
5. In case you are using dhclient, do the setup as follows
6. Remove dhclient-eth0.leases file, which mostly resides under /var/lib/dhcp where eth0 is the interface name.
7. In case you are using dhcpcd/pump, Edit /sbin/ifup script
8. See if the call to dhcpcd and pump include a -h $HOSTNAME switch. If they do not, add them, so the calls looks as follows
9. /sbin/dhcpcd -i $DEVICE -h $HOSTNAME
   or
   /sbin/pump –i $DEVICE -h $HOSTNAME
10. Remove all the files under /etc/dhcpc directory, like *.cache, *.org and *.info
11. Remove un-neccessary entries from /etc/hosts such that it looks like
12. 127.0.0.1 localhost localhost.localdomain
13. Restart the network service
14. /etc/init.d/network restart
    or
15. service restart network
16. Check the IP Address using ifconfig eth0
17. Do a nslookup to see whether the IP points to the new hostname.
18. eg. $> nslookup 155.123.33.23 It should be pointing to the new hostname.