In Cisco IOS, which command displays live RIP routing update activity so that you can see advertisements as they are sent and received?

Introduction / Context:
When troubleshooting distance vector routing protocols such as RIP, it is often helpful to observe actual routing updates as they are sent and received by the router. Cisco IOS includes debug commands that provide real time information about protocol activity. Knowing which debug command to use for RIP is an important troubleshooting skill.

Given Data / Assumptions:

• RIP is enabled and configured on the router interfaces.
• You want to see the contents of RIP updates in real time.
• You are working at a privileged EXEC prompt, such as Router#.
• You understand that debug commands can generate substantial output and should be used carefully.

Concept / Approach:
The debug ip rip command specifically enables debugging of RIP routing updates. When this command is active, the router displays messages whenever it sends or receives RIP packets, including information about routes and metrics. This is different from show ip route, which displays the already installed routes in the routing table, and show protocols, which gives summary status about configured routing protocols.

Step-by-Step Solution:
Step 1: From the Router# prompt, enter the command debug ip rip.Step 2: IOS begins printing messages to the console or terminal every time a RIP update is sent or received.Step 3: Observe the output to verify that the router is advertising the correct networks and receiving expected routes from neighbors.Step 4: If you need to stop the debugging output, use the command undebug all or no debug all.Step 5: Use the information gathered to diagnose issues such as missing routes, incorrect metrics, or misconfigured network statements.

Verification / Alternative check:
To confirm that debugging is active, you can use the command show debugging, which lists enabled debug options. You should see RIP listed as active. After finishing troubleshooting, always verify that debugging has been turned off to avoid excessive CPU usage and console spam.

Why Other Options Are Wrong:
Option A, show ip route, displays the current routing table but does not show the raw updates as they are exchanged.Option C, show protocols, gives a summary of the protocols running on the router and basic interface status, not live updates.Option D, debug ip route, is not the standard command for RIP updates and may not exist or would have a different purpose.Option E, show ip rip database, can display the RIP learned routes but not the live update packets as they are transmitted.

Common Pitfalls:
Debug commands can be powerful but also dangerous if used on busy production routers because they consume CPU resources and can flood the console. Always apply debug ip rip carefully, consider using logging buffered, and remember to turn debugging off when you are done.

Final Answer:
The command that displays live RIP routing updates is debug ip rip.