Instruction Manual

Module 9 Summary

Before students begin Module 10, they must be able to read and interpret a routing table and

must have mastered a range of IOS commands for troubleshooting.

Online assessment options include the end-of-module online quiz in the curriculum and the

online Module 9 exam. Paper activities and hands-on router challenges should be used to give

students troubleshooting practice. Consider giving students previously-bugged configuration

files so they can demonstrate their troubleshooting skills in a timed, controlled setting.

Students should understand the following main points:

• Use and understand the output of the show ip route command

• Determine the gateway of last resort

• Determine the route source and destination address

• Determine the route administrative distance

• Determine the route metric

• Determine the route next hop

• Determine the last route update

• Observe multiple paths to a destination

• Use a structured approach to troubleshooting

• Test by OSI layers

• Use indicators to troubleshoot Layer 1

• Use the ping command to troubleshoot Layer 3

• Use the telnet command to troubleshoot Layer 7

• Use the show interfaces command to troubleshoot Layer 1 and Layer 2

• Use the show ip route and show ip protocols commands to troubleshoot

routing issues

• Use the following commands to troubleshoot various router problems:

– show cdp

– traceroute

– show controllers serial

– debug