Why network tools diagnose connectivity in Linux CLI - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a host is reachable using ping.

Linux CLI

ping -c 4 [1]

Drag options to blanks, or click blank then click option'

A-t

B-v

Clocalhost

Dgoogle.com

Attempts:

3 left

💡 Hint

Common Mistakes

Using options like -v or -t instead of a hostname.

Leaving the host blank.

The ping command followed by a hostname or IP address checks connectivity by sending packets. Here, google.com is a common host to test.

2fill in blank

medium

Complete the command to display the current network interfaces and their IP addresses.

Linux CLI

ip [1]

Drag options to blanks, or click blank then click option'

Aaddr

Broute

Clink

Dconfig

Attempts:

3 left

💡 Hint

Common Mistakes

Using ip route which shows routing tables.

Using ip link which shows interfaces but not IP addresses.

The ip addr command shows network interfaces and their IP addresses, helping diagnose connectivity issues.

3fill in blank

hard

Fix the error in the command to trace the route packets take to reach a host.

Linux CLI

traceroute [1]

Drag options to blanks, or click blank then click option'

A-n

Bgoogle.com

C-c 4

Dlocalhost

Attempts:

3 left

💡 Hint

Common Mistakes

Using options like -n or -c without specifying a host.

Leaving the host blank.

The traceroute command requires a hostname or IP address to trace the path packets take. Here, google.com is the target host.

4fill in blank

hard

Fill both blanks to create a command that shows active network connections and listening ports.

Linux CLI

netstat [1] [2]

Drag options to blanks, or click blank then click option'

A-t

B-u

C-l

D-a

Attempts:

3 left

💡 Hint

Common Mistakes

Using only -t or -u which show TCP or UDP but not all connections.

Mixing options that don't show listening ports.

The netstat -a -l command lists all active connections and listening ports, useful for diagnosing network issues.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps interface names to their IP addresses if the IP is IPv4.

Linux CLI

interfaces = { [1]: [2] for [3], [2] in ip_addr.items() if '.' in [2] }

Drag options to blanks, or click blank then click option'

Aiface

Bip

Dip_addr

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same variable name for key and value.

Not filtering for IPv4 addresses.

This dictionary comprehension loops over ip_addr.items(), assigning interface names to iface and IPs to ip. It keeps only IPv4 addresses containing a dot.

Practice

1. What is the main purpose of using network tools like ping and traceroute?

easy

A. To change your computer's screen resolution

B. To install new software on your computer

C. To delete files from your system

D. To check if your computer can reach another device or website

Solution

1. Step 1: Understand what network tools do

   Network tools like ping and traceroute test connectivity between your computer and other devices or websites.

2. Step 2: Identify the correct purpose

   They help find if a connection is working or where it might be failing, not for installing software or changing settings unrelated to networking.

3. Final Answer:

   To check if your computer can reach another device or website -> Option D

4. Quick Check:

   Network tools diagnose connectivity = A [OK]

Hint: Network tools test connection, not system settings [OK]

Common Mistakes:

• Thinking network tools install software
• Confusing network tools with system utilities
• Assuming network tools change display settings

2. Which of the following is the correct syntax to send 4 ping requests to example.com?

easy

A. ping -c 4 example.com

B. ping example.com -count 4

C. ping /n 4 example.com

D. ping example.com -4

Solution

1. Step 1: Recall ping command options

   The option -c specifies the count of ping requests in Linux.

2. Step 2: Match correct syntax

   Only ping -c 4 example.com uses the correct option and order.

3. Final Answer:

   ping -c 4 example.com -> Option A

4. Quick Check:

   Count option for ping = -c [OK]

Hint: Use -c to set ping count in Linux [OK]

Common Mistakes:

• Using Windows ping options on Linux
• Placing options after the hostname incorrectly
• Using wrong option flags like /n or -count

3. What output will you get when running ping -c 1 8.8.8.8 if the network is working?

medium

A. Request timed out.

B. Permission denied

C. 1 packets transmitted, 1 received, 0% packet loss

D. Unknown host 8.8.8.8

Solution

1. Step 1: Understand ping output on success

   If the network works, ping shows packets sent and received with 0% loss.

2. Step 2: Identify correct output

   1 packets transmitted, 1 received, 0% packet loss matches the success message showing 1 packet sent and received with no loss.

3. Final Answer:

   1 packets transmitted, 1 received, 0% packet loss -> Option C

4. Quick Check:

   Successful ping = packets received with 0% loss [OK]

Hint: Success ping shows packets received and 0% loss [OK]

Common Mistakes:

• Confusing timeout message with success
• Thinking unknown host means network is fine
• Ignoring packet loss details

4. You run traceroute google.com but get the error: command not found. What is the best way to fix this?

medium

A. Install the traceroute tool using your package manager

B. Restart your computer

C. Use ping google.com instead

D. Change your DNS server settings

Solution

1. Step 1: Understand the error meaning

   command not found means traceroute is not installed or not in PATH.

2. Step 2: Fix by installing traceroute

   Installing traceroute with the package manager adds the command to your system.

3. Final Answer:

   Install the traceroute tool using your package manager -> Option A

4. Quick Check:

   Missing command = install tool [OK]

Hint: Install missing tools when command not found error appears [OK]

Common Mistakes:

• Restarting without checking installation
• Using ping when traceroute is needed
• Changing DNS without cause

5. You want to check if your computer's network interface has an IP address assigned. Which command helps diagnose this?

hard

A. ping 127.0.0.1

B. ip addr show

C. nslookup google.com

D. traceroute 8.8.8.8

Solution

1. Step 1: Understand what each command does

   ip addr show displays network interfaces and their IP addresses. ping 127.0.0.1 tests local network stack. nslookup checks DNS resolution. traceroute traces route to a host.

2. Step 2: Identify command to check IP address

   Only ip addr show directly shows assigned IP addresses on interfaces.

3. Final Answer:

   ip addr show -> Option B

4. Quick Check:

   Check IP address = ip addr show [OK]

Hint: Use ip addr show to see IP addresses on interfaces [OK]

Common Mistakes:

• Using ping to check IP assignment
• Confusing DNS lookup with IP address check
• Using traceroute for interface info