Different Network Troubleshooting Techniques

Learning network troubleshooting techniques is essential for anyone applying for roles such as a cloud administrator, cloud technician, network support specialist, or cloud support associate. Maintaining your organization’s computer network, ensuring optimal performance, and promptly addressing any issues is your responsibility.

Serious issues with the computer network can cause downtime, disrupt business operations, and slow productivity. 

This article shares the most common troubleshooting techniques. To gain hands-on experience, consider enrolling in an IT technician training program at an IT technician school.

Connectivity Tests

Connectivity tests are performed to check whether the device is reachable. You also need to determine the health of the network connection. The following are the two essential tools to test the connection:

Ping

Ping is a command-line utility that tests whether a device is reachable over the network. Depending on the operating system, the ping provides the following information:

• Reply status (Reply from [IP address] or Request timed out)
• IP address of the target
• Round-Trip Time (RTT)
• TTL (Time to Live)
• Packet statistics

Traceroute

It is a network testing tool that displays the path data takes to reach the destination device from your device. Traceroute provides the following information:

• List of hops (routers/gateways)
• IP address (and hostname, if resolvable) of each hop
• Round-trip times (RTT)
• Indicators of unreachable hops

Checking IP Configuration and DNS 

The target device may not communicate if it has an incorrect IP address, subnet mask, or default gateway. Sometimes, the system fails to resolve domain names into IP addresses due to incorrect Domain Name System (DNS) settings. The following built-in command-line tools help in troubleshooting these issues:

Tool	Platform	Description
ipconfig	Windows	Displays IP address, subnet mask, default gateway, and DNS settings Verifies network adapter configuration
ifconfig	Linux / macOS	Shows interface details such as IP address, broadcast address, and network mask Helps in checking and troubleshooting network interfaces
nslookup	Cross-platform	Queries DNS servers directly to test DNS resolution
dig	Linux / macOS	Provides detailed DNS query results Displays response times and authoritative DNS servers

Hardware and Physical Checks 

Sometimes, hardware issues such as damaged or loose cables, malfunctioning switches, or faulty network interface cards (NICs) can lead to network problems. 

To troubleshoot such issues, make sure that 

• All Ethernet cables are undamaged, securely connected, and functioning properly.
• All routers and switches are on, properly configured, and show normal status indicators.
• The operating system recognizes network interface cards, and the cards function properly.

Loopback testing is a technique used to find out if the connectivity issues are caused by NICs or some other part of the network.

Port Scanning and Firewall Checks

A port is a virtual endpoint (a numerical identifier) used to identify specific services or applications on a device for proper communication over a network. Sometimes, a device fails to access a certain service because a firewall has closed or blocked the required port. The following are the two key tools used to check ports and firewall:

Tool	Platform	Description
nmap	Cross-platform	Detects open ports on a device Identifies the running services
netstat	Windows / Linux / macOS	Displays active connections and listening ports on the local machine Helps in verifying whether applications are listening on the expected ports Detects unexpected or unauthorized connections

Performance and Bandwidth Testing

The following key factors affect the performance of a network:

Latency

Latency refers to the time it takes for a data packet to travel from its source to its destination. High latency can cause delays and negatively impact the performance of applications such as video conferencing.

Packet Loss

Sometimes, some data packets fail to reach the destination, which can disrupt streaming, VoIP calls, or file transfers.

Throughput

Throughput is the amount of data successfully transmitted over the network within a given time period (without loss, corruption, or retransmission). Low throughput slows down the network.

Tools for testing network performance and bandwidth:

Tool	Platform	Description
iperf	Cross-platform	Measures network bandwidth Tests throughput between two devices Helps identify whether the network can handle expected traffic levels
Wi-Fi analyzers	Windows / macOS / Android / iOS	Measures Wi-Fi signal strength Detects interference and channel usage Helps optimize wireless network performance

Monitoring and Packet Analysis

Real-time monitoring and packet analysis help detect performance issues, configuration errors, and security threats.

Key tools for monitoring and packet analysis:

Tool	Platform	Description
Wireshark	Windows / Linux / macOS	Graphical tool for capturing and analyzing network packets Displays detailed information (source/destination addresses, protocols, payload content) Helps identify traffic patterns, errors, or suspicious activity
tcpdump	Linux / macOS (available on Windows with ports)	Command-line tool for capturing and inspecting network traffic Lightweight and effective for troubleshooting on servers Useful for diagnosing complex issues and monitoring live traffic

Using Logs and Routing Verification

Device Logs

You can identify patterns, such as ports being blocked by a firewall, by reviewing logs of routers, switches, and firewalls.

Routing Tables

Each router uses a routing table to determine the most efficient path for transmitting packets over the network. For example, if a device is unable to communicate with another device, you can verify whether the correct path exists using routing tables.

Subnet Configurations

Sometimes, devices fail to communicate because of incorrect subnet masks or overlapping subnets. Verify that each network segment has a unique address space to ensure smooth routing.