Hi Sony,
This works fine on my fedora system...
Actually "rc.local" will be executed on bootup after all init scripts are completed. However, Try checking /sbin/iptables -L (which will list all IP addresses blocked) after a fresh reboot. The logs should ideally show that given IP packet is dropped.
Logs of iptables (for orkut.com) on my Fc7 system:
"Chain INPUT (policy ACCEPT)
target prot opt source destination
DROP 0 -- pq-in-f94.google.com anywhere
DROP 0 -- pq-in-f87.google.com anywhere
DROP 0 -- pq-in-f86.google.com anywhere
DROP 0 -- pq-in-f85.google.com anywhere
ACCEPT udp -- anywhere anywhere udp dpt:domain
ACCEPT tcp -- anywhere anywhere tcp dpt:domain
ACCEPT udp -- anywhere anywhere udp dpt:bootps
ACCEPT tcp -- anywhere anywhere tcp dpt:bootps
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination"