#CCNA Tshoot Drill: OSPF Hello Timer Changed

By certskills January 27, 2014 10:45

For this final variation of a #CCNA Simlet question in this series, consider what happens when one OSPF neighbor changes its OSPF Hello interval. Based on what you expect to change, what show command output should change? Prep for those Simlet questions again with today’s post (the question) and the following answer post.

Earlier posts in this series:

None, but there is a series that details the benefits and needs for these troubleshooting drills. Check this post for some comments about the usefulness of troubleshooting drills and how to create these for yourself.

Troubleshooting Drill Overview

All the troubleshooting drills begin with:

  1. A topology diagram for the network
  2. The correct working configuration for the relevant devices
  3. The list of changes made to the configuration

Your job in these drills is to imagine that you have a Sim or Simlet question on the exam that uses the topology and configuration as described (including the changes). Then, focus on show commands, assuming that the exam did not let you look at the configuration at all. Then answer for yourself:

  1. Which show commands will tell me relevant information in this scenario?
  2. What will be different in the show command output, comparing the working configuration (after step 2), versus the output taken after making the configuration changes (after step 3)?

Setup: Topology and Working Configuration

This drill uses the same base topology and configuration as some other drills, with the details repeated here for convenience. The figure shows the topology:

Figure 1: Topology Diagram


The following three examples list the configuration for the three routers.

Example 1: R1 Configuration


Example 2: R2 Configuration


Example 3: R3 Configuration


Note that while the PC can be assigned IP addresses and default gateway values, they do not matter to this exercise.

Configuration Changes for this Troubleshooting Drill

For this drill, imagine the scenario has been implemented as described so far in this blog post. Then, the configuration is changed, as follows:

R1: Interface S0/0/1’s OSPF Hello interval is changed to 11 seconds. That is, the configuration commands interface s0/0/1 and ip ospf hello-interval 11 are issued in sequence.

Your Tasks

Your tasks are relatively straightforward, as follows:

  1. Think, without your notes. What commands identify relevant information about this scenario? Make a list of the commands. Then look at your notes to complete your list.
  2. Which of those will have different information due to this change? Which will show no differences? For those whose output changes, what changes do you expect to see?


VLSM Design Drill #2
Answer Part 1: VLSM Design Drill #2
By certskills January 27, 2014 10:45
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  1. ibrahim khalil ba January 15, 09:52

    Hello Wendell,

    I’ve noticed something which seems to me a typo on 2 network commands in the post:

    R3: network area 0
    R2: network area 0

    Both sentences hane an extra “0” on the prefix part.

    Also, both ends of the R1-R3 have the clock rate 1536000 interface subcommand.

    Was this done on purpose ?

    Reply to this comment
    • certskills Author January 21, 11:17

      Hi Ibrahim,
      Thanks for the note! No, those were simply mistakes. Just fixed them. Thanks for the heads up!

      Reply to this comment
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