Troubleshooting Network Connectivity

A Practical Guide for the IT Specialist

A practical guide to diagnosing and resolving common network problems, from physical connection issues to logical configuration errors, using standard command-line tools.
Author

Chuck Nelson

Published

November 13, 2025

1 Purpose

Network problems are among the most common issues reported to IT support. A user who “can’t get to the internet” could be experiencing one of a dozen different failures. This document provides a systematic approach to network troubleshooting, starting from the user’s machine and working outwards, using a core set of universally available command-line tools.

2 What You’ll Learn

By the end of this reading, you will be able to:

  • Recognize common symptoms of network connectivity issues.
  • Follow a systematic, layered approach to troubleshoot network problems.
  • Use the ipconfig (Windows) and ip (Linux) commands to verify a device’s IP configuration.
  • Use the ping command to test basic connectivity to other devices.
  • Use the tracert (Windows) or traceroute (Linux) commands to map the path a packet takes to a destination.

This reading maps to the following program and course learning outcomes:

  • Program Learning Outcomes (PLOs):
    • 6. Maintain environment: This document focuses on the core troubleshooting processes for maintaining network connectivity and resolving user-reported issues.
  • Course Learning Outcomes (CLOs):
    • 3. Troubleshoot hardware and basic network components: This guide provides a direct, practical application of troubleshooting skills to common networking problems.

This exercise develops the following skills, which align with the O*NET SOC Code 15-1232.00 for Computer User Support Specialists.

Learning Objective O*NET KSAs Technologies Used
Systematically troubleshoot network faults. Knowledge: Telecommunications, Computers & Electronics
Skills: Troubleshooting, Critical Thinking		 ipconfig, ping
Use command-line tools to diagnose connectivity. Knowledge: Telecommunications
Abilities: Problem Sensitivity, Information Ordering		 tracert, nslookup

3 The Universal Symptom: “I Can’t Connect”

While the symptom is simple, the cause can be complex. The key is to determine the scope of the problem. Is it just this user? Is it the whole office? Is it just one website or all websites? A good troubleshooter works in layers, starting with the most local and likely causes.

4 A Systematic Troubleshooting Approach

When a user reports a network issue, follow this six-step process to isolate the problem.

4.1 Step 1: Check the Physical Layer (Is it plugged in?)

This is the simplest but most common point of failure. - Wired: Is the Ethernet cable securely plugged into both the computer’s NIC and the wall jack (or switch)? Is there a link light on the NIC, typically a solid or blinking green light, indicating a physical connection? - Wireless: Is the Wi-Fi turned on? Is the device connected to the correct Wi-Fi network (SSID)?

4.2 Step 2: Check the Local IP Configuration (ipconfig / ip addr)

If the physical connection seems okay, the next step is to see if the computer has a valid IP address from the DHCP server.

  • Windows: Open a Command Prompt and type ipconfig.
  • Linux/macOS: Open a terminal and type ip addr or ifconfig.

Look for the active network adapter (e.g., “Ethernet adapter” or “Wireless LAN adapter”). You should see an IPv4 Address, a Subnet Mask, and a Default Gateway.

  • Valid IP: If you see an address like 192.168.1.150, you have a valid configuration.
  • APIPA Address: If the IP address starts with 169.254.x.x, this is an Automatic Private IP Addressing (APIPA) address. It means your computer could not contact the DHCP server and assigned itself a random, non-routable address. This points to a problem with the DHCP server or the connection to it.

4.3 Step 3: Test Local Network Connectivity (ping the Gateway)

The Default Gateway is the IP address of your local router. If you can “ping” it, you know that your computer can communicate with the router, and your local network is likely working. The ping command sends a small packet to a destination and waits for a reply.

  • ping 192.168.1.1 (Replace with the actual Default Gateway address from ipconfig).

  • Successful Ping: You will see replies like “Reply from 192.168.1.1: bytes=32 time<1ms TTL=64”. This confirms your local network is okay. The problem lies further out.

  • Failed Ping: You will see “Request timed out” or “Destination host unreachable.” This confirms the problem is on your local network, between your computer and the router.

4.4 Step 4: Test Internet Connectivity (ping an External Address)

If you can ping your local router, the next step is to see if you can reach the internet at all. The easiest way is to ping a reliable public IP address, like one of Google’s DNS servers.

  • ping 8.8.8.8

  • Successful Ping: You get replies. This means your router has a working connection to the internet. The problem is not with general connectivity, but likely with DNS.

  • Failed Ping: You get timeouts. This means your local router cannot reach the internet. The problem is with your router’s configuration or your Internet Service Provider (ISP).

4.5 Step 5: Test DNS Resolution (ping a Domain Name)

If you can ping 8.8.8.8 but you can’t browse to websites, the problem is almost certainly DNS. DNS is what translates www.google.com into an IP address.

  • ping www.google.com

  • Successful Ping: The name resolves to an IP address and you get replies. If you can do this but still can’t browse, the issue might be a web browser proxy setting or a firewall blocking web traffic.

  • Failed Ping: You see an error like “Ping request could not find host www.google.com.” This is the classic sign of a DNS failure. Your computer was unable to translate the name into an IP address. You can try flushing your local DNS cache (ipconfig /flushdns on Windows) or changing your DNS server settings.

4.6 Step 6: Trace the Path (tracert / traceroute)

If pings are failing to a specific destination, the tracert (Windows) or traceroute (Linux) command can help you find out where the problem is. It shows you every “hop” (router) a packet passes through on its way to the destination.

  • tracert www.google.com

You will see a list of routers. If the trace suddenly stops and you see timeouts (* * *), the failure is likely at the last router that responded. This is an advanced tool but can be invaluable for diagnosing problems on the wider internet.

5 Reflect and Review

ImportantReflection: 3-2-1

Now that you have reviewed this document, take a moment to reflect on your learning in your Microsoft Teams Student Notebook:

  • 3 command-line tools used for network troubleshooting.
  • 2 possible interpretations of a failed ping command.
  • 1 question you still have about interpreting tracert results.
TipCheck on Learning

Answer these questions in your notebook to solidify your understanding:

  1. You run ipconfig and see your IP address is 169.254.100.54. What does this mean?
  2. You can successfully ping your default gateway, but you cannot ping 8.8.8.8. Where is the most likely location of the problem?
  3. You can successfully ping 8.8.8.8, but you get a “host not found” error when you try to ping www.google.com. What is the most likely problem?
  4. What is the first, most basic step you should always check when a user reports they have no network connection?
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