Chapter 5 of 6 · Cisco CCST 100-150 Networking
Diagnosing Problems
Troubleshooting method, Wireshark, diagnostic commands, device access and Cisco show commands.
- 6topics
- 27 minfast track
- 2diagrams and exhibits
Topics in this chapter
Take them in order, or jump to the one you need.
- 1Troubleshooting Methods and Help Desk PracticeLearn a step by step troubleshooting method, how help desk ticketing and documentation work, and how to gather information and…4 min
- 2Packet Capture with WiresharkLearn what a packet analyzer does, how to capture traffic with Wireshark, use simple display filters, and save and reopen a .pcap…4 min
- 3Diagnostic Commands and Reading the ResultsRun ping, ipconfig, ifconfig, ip, tracert, traceroute and nslookup, interpret their results, and see how firewalls can change…Diagram5 min
- 4Accessing and Collecting Data from Network DevicesCompare RDP, SSH, telnet, VPN, console, terminal emulators, network management systems, cloud managed Meraki and scripts for…Diagram5 min
- 5Basic Cisco Show CommandsRead Cisco IOS show commands such as show running-config, show ip interface brief, show ip route, show mac address-table and show…5 min
- 6Privilege Levels, Command Help and Auto-CompleteLearn the Cisco IOS user and privileged EXEC modes, privilege levels, how question mark help works, and how auto-complete and…4 min
About this chapter
What this chapter covers
Diagnosing Problems is about how a support technician finds out what is wrong with a network.
It covers the way to approach a problem, and the tools to investigate it. These include a packet analyzer, the common diagnostic commands, the ways to reach a device, and the show commands on a Cisco switch or router.
This is the most hands on chapter of the guide. You will get the most from it by trying the commands on a real computer or in a simulator.
How the topics fit together
A method comes first, and the tools fit into its steps.
The first page covers troubleshooting and help desk practice. It gives the steps to follow, and explains tickets, documentation and priority.
The second page covers Wireshark, which lets you look inside the traffic. The third page covers the diagnostic commands such as ping, which test the network from a computer.
The fourth page compares the ways to reach a device, from console to cloud dashboards. The last two pages cover the Cisco show commands, and the privilege levels and help system that you use to run them.
Several topics build on earlier chapters. The diagnostic commands use the addressing ideas from chapter two, and the show commands use the switching and routing ideas from the infrastructure chapter.
How to use these pages
Each topic page has the same shape, so you can skim for what you need.
- What it is: the idea in plain words.
- How it works: the mechanism, with diagrams, tables and example output.
- What to remember for the exam: the facts to memorise.
- Common mistakes: the classic traps.
- Check yourself: three questions to test your understanding.
Run each command yourself and compare your output with the examples. Real devices differ a little from the samples, and spotting the differences is good practice.
Ready for more practice?
The full Cisco CCST 100-150 Networking question bank has 749 questions, with timed practice exams and an explanation for every answer.
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