Here are the simple steps to follow to block a website to the user who are accessing Internet through your Router Step 1: Configure a DNS server Let’s say we want to block access to the creatively named www.block-site.com. We don’t know the IP address, and we don’t want to know it. When we configure the Access List in the router—the Cisco IOS can look it up and fill it automatically. To do this, we need at least one DNS server configured on the router. To configure a DNS server, use the ip name-server command. Here’s an example: Router(config)# ip name-server 1.1.1.1 2.2.2.2 In this case, we configured a primary and a backup DNS server for the router to use to resolve DNS names. This doesn’t affect any traffic flowing through the router; the router will use these DNS servers when we ping a Web server by name. Here’s an example: Router# ping www.khatrinetworks.blogspot.com Translating “www.khatrinetworks.blogspot.com”…domain server (1.1.1.1) [OK] Type escape sequence to abort.
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