One way that pharming takes place is via an e-mail virus that "poisons" a user's local DNS cache. It does this by modifying the DNS entries, or host files. For example, instead of having the IP address 17.254.3.183 direct to www.apple.com, it may direct to another website determined by the hacker. Pharmers can also poison entire DNS servers, which means any user that uses the affected DNS server will be redirected to the wrong website. Fortunately, most DNS servers have security features to protect them against such attacks. Still, they are not necessarily immune, since hackers continue to find ways to gain access to them.