Cisco Certified Network Associate (CCNA) Practice Exam

What is the first step to configure authentication on an EIGRP router?

1. (config)#interface INTERFACE

2. (config)#key chain KEY CHAIN NAME

3. (config)#router eigrp 1

4. (config)#authentication key-chain EIGRP 1

The correct answer is: (config)#key chain KEY CHAIN NAME

To configure authentication on an EIGRP (Enhanced Interior Gateway Routing Protocol) router, the first step is to create a key chain using the command that specifies the name of the key chain. This step is essential because the key chain is where the authentication keys will be defined and managed. The process starts by establishing a key chain, as it encapsulates the keys that will be used for authenticating EIGRP packets between routers. The keys must be configured to ensure that both routers that are peering and exchanging routes can authenticate each other. Without this initial setup, the subsequent steps involved in enabling authentication for EIGRP cannot be executed effectively. After defining the key chain, you would typically proceed to the router configuration mode for EIGRP and link the authentication to the EIGRP process to enforce the security measures. Therefore, creating a key chain is a foundational step that must be completed before EIGRP can properly implement its authentication mechanism.