chaz@ultra:~$ host 199.255.210.75
75.210.255.199.in-addr.arpa domain name pointer 199-255-210-75.anchorfree.com.
chaz@ultra:~$ host 199-255-210-75.anchorfree.com
199-255-210-75.anchorfree.com has address 68.68.107.160
199-255-210-75.anchorfree.com has address 68.68.107.161
You should probably block:
*.anchorfree.com
68.68.107.*
199.255.209.*
199.255.210.*
199.255.211.*