CompTIA Network+

CompTIA Network+ domain 5: Network troubleshooting and tools

February 28, 2019 by Greg Belding

The CompTIA Network+ certification can help bring your career to the next level and is a strong professional asset to have on your side. To earn this certification, you have to pass the Network+ certification exam. This exam is comprised of five different Domains of knowledge that certification candidates will need to master.

This article will detail Domain 5.0 — Network Troubleshooting and Tools, complete with its different objectives and what material you will need to cover. This article should not serve as your sole means of preparing for the Network+ certification exam, but rather as a general review or an outline foundation.

Network troubleshooting and tools outline

The following subtopics can be expected to be tested in the Network Troubleshooting and Tools domain:

5.1 Network Troubleshooting Methodology

5.2 Appropriate Tools for Different Scenarios

5.3 Troubleshooting Common Wired Connectivity/Performance Issues

5.4 Troubleshooting Common Wireless Connectivity/Performance Issues

5.5 Troubleshooting Common Network Service Issues

Network troubleshooting methodology

Many do not notice that the scientific method is reflected in network troubleshooting. For a refresher, the scientific method is:

  1. Identifying the problem
  2. Researching said problem
  3. Hypothesis creation
  4. Testing a solution
  5. Analysis of said solution
  6. Conclusion

These steps match up to certain network troubleshooting steps. Network troubleshooting steps are listed below:

  • Identify the problem
    • Gather information
    • Duplicate the problem if possible
    • Identify symptoms
    • Questions users
    • Determine if there have been any changes
    • Approach multiple problems individually
  • Establish a theory of probable cause
    • Consider the obvious
    • Consider multiple approaches/keep an open mind
  • Test the theory to determine the cause
    • After confirming theory, determine next steps in resolution
    • If theory is not confirmed, either establish a new theory or escalate
  • Establish a plan of action to resolve problem and identify potential effects
  • Implement the solution or escalate as needed
  • Verify full system functionality and implement preventive measures if applicable
  • Document findings, actions and outcomes

Appropriate tools for different scenarios

There are two main categories of tools: software and hardware. Software tools are normally used to troubleshoot, and hardware tools are used to both troubleshoot and repair.

Hardware tools

  • Crimper
  • Cable tester
  • Punchdown tool
  • OTDR
  • Tone generator
  • Light meter
  • Loopback adapter
  • Multimeter
  • Spectrum analyzer

Software tools

  • Port scanner
  • Packet sniffer
  • Protocol analyzer
  • Wi-Fi analyzer
  • Bandwidth speed tester

Command line

The command line is the most covered of the software tools. The commands you will be responsible for include:

  • Ping
  • Tracert/traceroute
  • Nslookup
  • Ipconfig
  • Ifconfig
  • Iptables
  • Netstat
  • Tcpdump
  • Nmap
  • Pathping
  • Route
  • Dig
  • Arp

Troubleshooting common wired connectivity/performance issues

There are many scenarios where issues can plague your wired network. Being a wired network brings its own problems despite the seeming simplicity of wired network concepts. These connectivity and performance issues need to be explained using the tools mentioned in the subsections above. You will be responsible for explaining how to troubleshoot the following:

  • Attenuation
  • Latency
  • Crosstalk
  • Jitter
  • EMI
  • Open and short
  • Incorrect pin-out
  • Bad port
  • Incorrect cable type
  • Transceiver mismatch
  • TX/RX reverse
  • Duplex/speed mismatch
  • Damaged cables
  • Damaged pins
  • Bottlenecks
  • Network connection LED status indicators
  • VLAN mismatch

Troubleshooting common wireless connectivity/performance issues

Wireless networks are becoming more of a go-to as opposed to a novelty relegated to the realm of free Wi-Fi for your customers. However, with wireless networks comes its own connectivity and performance issues. Keep in mind that these connectivity and performance issue can be solved using the tools that were discussed in 5.2. The wireless network troubleshooting for connectivity and performance issues that you need to be able to explain are:

  • Reflection
  • Refraction
  • Absorption
  • Latency
  • Jitter
  • Attenuation
  • Incorrect antenna type
  • Interference
  • Incorrect antenna placement
  • Channel overlap
  • Overcapacity
  • Distance limitations
  • Frequency mismatch
  • Wrong SSID
  • Wrong passphrase
  • Security type mismatch
  • Power levels
  • Signal-to-noise ratio

Troubleshooting common network service issues

If you work as a network administrator, then you know that troubleshooting common network service issues can be more complicated than you think. Yes, this subsection goes above and beyond giving your service provider a phone call to get them to resolve the issue. The troubleshooting of common network service issues that you will need to explain include:

  • Names not resolving
  • Incorrect gateway
  • Incorrect netmask
  • Duplicate IP addresses
  • Duplicate MAC addresses
  • Expired IP address
  • Rogue DHCP server
  • Untrusted SSL certificate
  • Incorrect time
  • Exhausted DHCP scope
  • Blocked TCP/UDP ports
  • Incorrect host-based firewall settings
  • Incorrect ACL settings
  • Unresponsive service
  • Hardware failure


The CompTIA Network+ exam covers five domains of knowledge, and among these domains is Network Troubleshooting and Tools. This final domain of the Network+ exam focuses on what many consider to be the bread and butter of network administration and this is an accurate view in many cases.

Keep in mind that this article is a very useful tool. Network+ can be a difficult exam for some — use this article as a guide and you will have a better chance at passing this exam and bolstering your career marketability.

Congratulations — you have reached the end of the last domain!


  • CompTIA Network+ Certification Exam Objectives, CompTIA
  • Buhagiar, Jon. “CompTIA Network+ Review Guide: Exam N10-007,” Sybex, 2018
  • Weissman, Jonathan S., Meyers, Mike. “Mike Meyers’ CompTIA Network+ Certification Passport, Sixth Edition (Exam N10-007) (Mike Meyers’ Certification Passport),” McGraw-Hill Education, 2018
Posted: February 28, 2019
Greg Belding
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Greg is a Veteran IT Professional working in the Healthcare field. He enjoys Information Security, creating Information Defensive Strategy, and writing – both as a Cybersecurity Blogger as well as for fun.

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