Cisco Certified Network Associate (CCNA) Practice Exam

What configuration will disable split horizon on an EIGRP router interface?

1. no ip split-horizon eigrp AS NUMBER

2. ip split-horizon eigrp AS NUMBER

3. ip no split-horizon eigrp

4. shut split-horizon eigrp

The correct answer is: no ip split-horizon eigrp AS NUMBER

The correct configuration to disable split horizon on an EIGRP router interface is the command that explicitly states “no ip split-horizon eigrp AS NUMBER.” This command directly disables the split horizon feature for EIGRP on the specified Autonomous System (AS) number and allows routes learned from one interface to be sent back out the same interface. Understanding split horizon is crucial in EIGRP because it helps prevent routing loops. However, in certain network designs such as those utilizing point-to-multipoint configurations or where multiple paths to a destination exist, it may be necessary to modify this behavior for proper route propagation. By using the correct command, you effectively communicate to the router that you wish to disregard the default behavior of not sending updates back out of the interface through which they were received. On the other hand, the other options presented do not achieve the correct configuration required to disable split horizon. For example, attempting to use a command that begins with “ip split-horizon eigrp AS NUMBER” would imply enabling the feature rather than disabling it, thus reinforcing the definition rather than modifying the configuration. Similarly, commands like “ip no split-horizon eigrp” or “shut split-horizon eigrp” do not align with