D-Link DFL-600 - Manual (Page 72)

Enter a domain name you want to limit access to in the Domain Name field.
Click the Apply button to add this domain name to the list.
Blocking Keywords
The DFL-600 will allow you to make a list of keywords for which packets
will be filtered
Clicking on the Keywords Add link on the Policy Rules page will open the
following page.
Enter a key word you want the DFL-600 to examine packets for in the Key
Word field. Click the Apply button to enter this key word into the list.