Blocking a domain based on names



Hi,

Is there any command to block domains based on their names like
marskarthik.com, mail.yahoo.com, etc in Cisco 2610 router or Cisco Pix
506E

Since these domain people change ip address often, i want to block
based on domain names.

Someone help me on this.

Thanks in advance,
Karthik(www.marskarthik.com)

.