Cisco Certified Network Associate (CCNA) Practice Exam

What is the meaning of the term dynamic as displayed in the output of the show frame-relay map command?

1. The mapping of the DLCI and the IP address is statically defined.

2. The mapping of the DLCI and the IP address was learned through Inverse ARP.

3. The mapping of the IP address is set to expire in a specified timeout period.

4. The mapping of the DLCI and the IP address was manually configured.

The correct answer is: The mapping of the DLCI and the IP address was learned through Inverse ARP.

The term dynamic in the context of the show frame-relay map command indicates that the mapping of the Data Link Connection Identifier (DLCI) to the IP address was learned through a process known as Inverse Address Resolution Protocol (Inverse ARP). Inverse ARP is a mechanism used in Frame Relay networks that allows a device to discover the network layer address (such as an IP address) that is associated with a particular DLCI. When a router sends out a request to find the IP address assigned to a DLCI, and receives a response, it dynamically builds the mapping based on the information it learns from the response. This process facilitates automatic mapping, which is particularly useful in environments where devices frequently join and leave the network or where the network configuration changes often. In contrast, if the mapping had been manually configured, it would be labeled as static, and if it were set to expire, it would involve some timeout mechanism that would not fall under the dynamic category. Thus, the correct answer accurately reflects how the mapping is established in this scenario.