Recently I found out that there are malicious websites that do not have a domain name on its own. For example, 18.104.22.168 as in http://googleonlinesecurity.blogspot.hk/2009/06/top-10-malware-sites.html
Other malware domain list site also shows that there are multiple malicious url that do not have a domain name, e.g. 22.214.171.124.
I would like to ask why do malicious website would try to post their website without domain name? I understand that without a domain name, a hacker can save more money. However, isn't the attacker more easy to be be found by Internet Police? Since the IP is already listed in the url and you do not even need to go for a DNS look up.
So why would this be? Can anyone tell me the reason? Thanks.