Chapter 1 · Computer Networks
1.11Network Diagnostic Tools and Commands
Commands that check a network: ping tests if a device answers, ipconfig and ifconfig show your settings, Telnet, PuTTY and SSH give remote access.
Written and checked by Muhammad Raheel(opens in a new tab)
Full Stack Developer · AI Engineer · Reviewed 21 Oct 2026 · 3 min read
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When the internet stops working, you need a way to look inside the network. Diagnostic tools do this. You type their commands in the Command Prompt (Windows) or the terminal (Linux and macOS), and they tell you what is wrong.
Finding and fixing the problem is called troubleshooting.
Troubleshooting looks at three things: cables, devices and settings. Good troubleshooting means less downtime, fewer errors and a faster network.
Ping Command
Ping asks another device a simple question: "Are you there?"
Ping sends small data packets to the other device and waits for an answer. It also measures how long the answer takes. A long time means the network has a delay. The book's example pings Google:
C:\> ping google.comThe book's sample output:
Pinging google.com [142.250.190.14] with 32 bytes of data:
Reply from 142.250.190.14: bytes=32 time=25ms TTL=118
Reply from 142.250.190.14: bytes=32 time=24ms TTL=118
Reply from 142.250.190.14: bytes=32 time=26ms TTL=118
Reply from 142.250.190.14: bytes=32 time=25ms TTL=118Line by line: the first line shows the IP address of google.com and the packet size, 32 bytes. Each "Reply from" line is one answer. bytes=32 is the size, time=25ms is the response time in milliseconds, and TTL=118 (time to live) shows how many more routers the reply could still pass through. Four replies mean Google is reachable.
Figure 1.16 in the book shows how this works. Host A (a laptop) sends an "ICMP Echo Request" to Host B (a server). Host B sends back an "ICMP Echo Reply".
The book's class activity asks you to map the path packets take between two places.
Ipconfig and ifconfig Commands
These commands answer the question "What are my own network settings?"
The book lists what they show: IP address, subnet mask, gateway and network status. This helps a lot in troubleshooting. For example, a strange IP address can show that the computer never connected to the router.
Telnet, PuTTY, and Secure Shell (SSH)
Sometimes you must control a device that is far away, like a router in another building. These tools let you log in to it over the network.
| Tool | What the book says |
|---|---|
| Telnet | used for remote device access; sends data without encryption |
| PuTTY | a popular tool for remote login |
| SSH | a secure method for remote access; encrypts data for safety |
The big difference is encryption. With Telnet, your password travels as plain text, so anyone watching the network can read it. SSH scrambles everything first. That is why SSH is used today.
Practice this topic
Short questions
1.What are network diagnostic tools?2 marks
Answer
From the book: "Network diagnostic tools are used to find network problems. They help check internet and network connections. These tools show whether devices can communicate properly." Their commands "are entered using the command prompt or terminal".
2.What is network troubleshooting? Write two of its benefits.3 marks
Answer
From the book: "Network troubleshooting is done to find and fix network issues." It "checks cables, devices, and settings". Benefits: "It reduces network downtime and errors. It helps maintain smooth communication. Proper troubleshooting improves network performance."
3.What is the use of the ping command?3 marks
Answer
From the book: "The ping command is used to test network connectivity. It checks if a device is reachable on the network. Ping sends small data packets to another device." "It measures response time from the destination. This command helps detect network delays. It is commonly used to check internet connection."
4.How does ping work, as shown in Figure 1.16?3 marks
Answer
Figure 1.16 (Ping Command) shows Host A (a laptop running "Ping 192.168.0.1") sending an "ICMP Echo Request" to Host B (a server). Host B sends an "ICMP Echo Reply" back to Host A. In the book's words: "Ping sends small data packets to another device" and "measures response time from the destination".
5.Write the difference between ipconfig and ifconfig.2 marks
Answer
From the book: "Ipconfig is used in Windows operating system. Ifconfig is used in Linux and macOS systems." Both "display network settings".
6.What information do the ipconfig and ifconfig commands display?2 marks
Answer
From the book: "These commands display network settings. They show IP address and subnet mask. They also show gateway and network status. These commands help in network troubleshooting."
7.Differentiate between Telnet and SSH.3 marks
Answer
From the book: "Telnet is used for remote device access. It sends data without encryption." "SSH is a secure method for remote access. SSH encrypts data for safety." So both give remote access, but only SSH encrypts the data.
8.What is PuTTY?2 marks
Answer
From the book: "PuTTY is a popular tool for remote login." Like Telnet and SSH, it helps manage network devices: "These tools help manage network devices."
Long questions
1.What are network diagnostic tools? Explain the ping command with the help of its sample output and Figure 1.16.8 marks
Answer
- Diagnostic tools (verbatim): "Network diagnostic tools are used to find network problems. They help check internet and network connections. These tools show whether devices can communicate properly. Commands are entered using the command prompt or terminal."
- Troubleshooting: "Network troubleshooting is done to find and fix network issues." It "checks cables, devices, and settings" and "reduces network downtime and errors".
- Ping (verbatim): "The ping command is used to test network connectivity. It checks if a device is reachable on the network. Ping sends small data packets to another device (as shown in Figure 1.16). It measures response time from the destination. This command helps detect network delays. It is commonly used to check internet connection."
- Command and sample output (copy as printed): the command is C:> ping google.com and the output starts "Pinging google.com [142.250.190.14] with 32 bytes of data:", followed by four lines such as "Reply from 142.250.190.14: bytes=32 time=25ms TTL=118". Explain: 32 bytes of data in each packet, time= is the response time, four replies mean the device is reachable.
- Figure 1.16: Ping Command: Host A sends an "ICMP Echo Request" to Host B; Host B sends an "ICMP Echo Reply" back.
Aim for 250-350 words.
2.Explain the ipconfig and ifconfig commands. Also describe Telnet, PuTTY, and Secure Shell (SSH).6 marks
Answer
- Ipconfig and ifconfig Commands (verbatim): "Ipconfig is used in Windows operating system. Ifconfig is used in Linux and macOS systems. These commands display network settings. They show IP address and subnet mask. They also show gateway and network status. These commands help in network troubleshooting."
- Telnet (verbatim): "Telnet is used for remote device access. It sends data without encryption."
- PuTTY (verbatim): "PuTTY is a popular tool for remote login."
- SSH (verbatim): "SSH is a secure method for remote access. SSH encrypts data for safety."
- Close: "These tools help manage network devices." A good answer compares Telnet (no encryption) with SSH (encrypts data).
Aim for 200-300 words.
In this chapter
- 1.1Introduction to Computer Networks
- 1.2Network Architecture and Basic Concepts
- 1.3Types of Computer Networks
- 1.4Networking Devices
- 1.5Network Topologies
- 1.6Network Models and Layers
- 1.7Network Protocols and Services
- 1.8IP Addressing and Subnetting
- 1.9Home Network Setup and Configuration
- 1.10Wi-Fi Security and Router Configuration
- 1.11Network Diagnostic Tools and CommandsYou are here
- 1.12Network Performance
- 1.13Network Load Balancing
- 1.14Network Security
- 1.15Data Backup and Recovery
- 1.16Usability and Security Tradeoffs