Which of the following is specifically filtered by a URL filtering subscription service on a Cisco router? (Select the best answer.)
- traffic sent from specific domains
- traffic that contains specific keywords
- traffic that contains malicious software
- traffic that matches predefined categories
On a Cisco router, traffic that matches predefined categories is filtered by a Uniform Resource Locator
(URL) filtering subscription service. URL filtering inspects Hypertext Transfer Protocol (HTTP) requests and blocks access to websites that match certain criteria. Subscriptionbased URL filtering services, which are offered by Trend Micro, Websense, and Secure Computing, assign websites to categories, which are used by administrators to limit or block access to these sites. URL filtering is commonly configured on perimeter routers to prevent users from inadvertently accessing URLs that have been deemed inappropriate or identified as containing malware.
Although a URL filtering subscription service does not specifically filter traffic that contains malicious software as a payload, you can configure the local URL filtering service so that access to websites known to distribute malicious software is filtered. For example, if a particular URL is known to harbor malware, you could filter that specific URL or the entire domain. However, to filter traffic that contains malicious software as a payload, you should install an Intrusion Prevention System (IPS).