| Summary

| An understanding of the following key points should have been achieved: The show ip route command Determining the gateway of last resort Determining the route source and destination address Determining route administrative distance Determining route metric Determining route next hop Determining last route update Observing multiple paths to destination Using a structured approach to troubleshooting Testing by OSI layers Layer 1 troubleshooting using indicators Layer 3 troubleshooting using ping Layer 7 troubleshooting using Telnet Troubleshooting Layer 1 using show interfaces Troubleshooting Layer 2 using show interfaces Troubleshooting using show cdp Troubleshooting using traceroute Troubleshooting routing issues using show ip route and show ip protocols Troubleshooting using show controllers serial Troubleshooting using debug commands