Normally, when we think about DNS, we think about dedicated DNS servers. But Cisco IOS routers can also provide useful DNS features. In this scenario, I built a small lab to test how a router can act as: The lab contains two DNS servers and two clients. One of the clients also works as a…

In this lab, I wanted to analyze a very specific use case: How can a router connected over a PPP serial link receive its IP address dynamically from a DHCP server that is not directly attached? What makes this lab interesting is that the DHCP client is connected through a PPP serial interface, not through…

In this lab, I wanted to analyze the behavior of the Cisco IOS interface command arp authorized. The idea behind this feature is that the router should not rely on normal dynamic ARP learning on that interface. Cisco documents this behavior by stating that arp authorized stops dynamic ARP on the interface. Because of that,…