How to redirect out going traffic to an IP address to another host name?
You don't specify whether you want to block incoming traffic from that host name or outgoing or both. You also don't mention what version of Mac OS X you are running and whether or not you are trying to block that host with a specific application like Little Snitch or similar. Some logs would be helpful as well. Consult this page to help you formulate better questions for the community to be able to answer. 

203.130.48.8-BJ-CNC is a valid hostname according to IETF standard RFC 952.  


  A "name" (Net, Host, Gateway, or Domain name) is a text string up
  to 24 characters drawn from the alphabet (A-Z), digits (0-9), minus
  sign (-), and period (.).


To block outgoing traffic to it, use the hostname in your /etc/hosts file like so:

127.0.0.1    203.130.48.8-bj-cnc


Then do:

sudo dscacheutil -flushcache


to load the new rules.

If you want to be able to block outgoing traffic to the actual ip address of the machine you'll need to use Mac's builtin packet filter (originally from OpenBSD's excellent PF. A pf.conf rule would look like this:

block out log quick on $ext_if proto { tcp, udp, icmp } to 203.130.48.8


Blocking incoming traffic from that ip is generally handled just fine by using Mac OS X's default application firewall in  -&gt; System Preferences -&gt; Security &amp; Privacy -&gt; Firewall. Alternatively you can set the policy via the commandline like so:

sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setblockall on


for thoroughness, you may also want to block all icmp requests:

sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setstealthmod on


and finally enable it thus:

sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setglobalstate on