A particularly ominous pharming tactic is known as domain name system poisoning (DNS poisoning), in which the domain name system table in a server is modified so that someone who thinks they are accessing legitimate Web sites is actually directed toward fraudulent ones. In this method of pharming, individual personal computer host files need not be corrupted. Instead, the problem occurs in the DNS server, which handles thousands or millions of Internet users' requests for URLs. Victims end up at the bogus site without any visible indicator of a discrepancy. Spyware removal programs cannot deal with this type of pharming because nothing need be technically wrong with the end users' computers.