ping for connectivity testing in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this ping command?

You run the command ping -c 3 8.8.8.8 on a Linux terminal. What will the output show?

Linux CLI

ping -c 3 8.8.8.8

A It sends 3 ping requests to 8.8.8.8 and shows 3 replies with round-trip times.

B It sends continuous ping requests until stopped manually.

C It shows an error because the -c option is invalid.

D It sends 3 ping requests but does not show any reply output.

💡 Hint

The -c option limits the number of ping requests sent.

The -c 3 option tells ping to send exactly 3 packets and then stop, showing replies and timing info.

💻 Command Output

intermediate

What error does this ping command produce?

What error message appears when running ping -c three 8.8.8.8?

Linux CLI

ping -c three 8.8.8.8

A ping: invalid count of packets: 'three'

B ping: unknown host three

C ping: option requires an argument -- 'c'

D No error, it sends 3 packets anyway.

💡 Hint

The -c option expects a number, not a word.

The -c option requires a numeric argument. Using 'three' causes an invalid count error.

📝 Syntax

advanced

Which ping command syntax correctly sends 5 packets to example.com?

Choose the correct ping command to send exactly 5 packets to example.com.

A ping example.com -count 5

B ping -c 5 example.com

C ping -count=5 example.com

D ping -n 5 example.com

💡 Hint

The standard option to specify count is -c followed by a number.

The correct syntax is 'ping -c 5 example.com'. Other options are invalid or for different OS.

🚀 Application

advanced

How to automate ping to check connectivity every 10 seconds for 1 minute?

You want to check if google.com is reachable every 10 seconds for 1 minute using ping. Which command achieves this?

A ping -w 60 -i 10 google.com

B ping -c 6 -i 1 google.com

C ping -i 10 -c 6 google.com

D ping -c 60 -i 10 google.com

💡 Hint

The -i option sets interval between packets, -c sets count.

Sending 6 packets (-c 6) every 10 seconds (-i 10) totals about 1 minute.

🧠 Conceptual

expert

What does the ping command's exit status indicate?

After running a ping command, what does an exit status of 0 mean?

A No replies were received; the host is unreachable.

B The ping command was interrupted by the user.

C The ping command failed due to invalid arguments.

D At least one reply was received from the target host.

💡 Hint

Exit status 0 usually means success in Linux commands.

Ping returns 0 if it receives any reply packets, indicating connectivity.

Practice

1. What does the ping command do in Linux?

easy

A. Displays the current directory contents

B. Checks if your computer can reach another device on the network

C. Deletes files from the system

D. Installs new software packages

Solution

1. Step 1: Understand the purpose of ping

   The ping command sends small packets to another device to check if it is reachable on the network.

2. Step 2: Compare options

   Only Checks if your computer can reach another device on the network describes this network connectivity check. Other options describe unrelated commands.

3. Final Answer:

   Checks if your computer can reach another device on the network -> Option B

4. Quick Check:

   Ping = Network reachability check [OK]

Hint: Ping tests connection by sending packets [OK]

Common Mistakes:

• Confusing ping with file or directory commands
• Thinking ping installs software
• Assuming ping deletes files

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

easy

A. ping example.com -c4

B. ping -n 4 example.com

C. ping -c 4 example.com

D. ping example.com -count 4

Solution

1. Step 1: Recall the option to limit ping count

   The -c option followed by a number limits the number of ping requests sent.

2. Step 2: Check each option

   ping -c 4 example.com uses -c 4 correctly. ping -n 4 example.com uses -n which is Windows syntax. ping example.com -count 4 uses incorrect syntax. ping example.com -c4 misses a space between -c and 4.

3. Final Answer:

   ping -c 4 example.com -> Option C

4. Quick Check:

   Use -c for count in Linux ping [OK]

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

Common Mistakes:

• Using Windows ping options like -n
• Missing space between option and number
• Using incorrect option names

3. What will be the output of the command ping -c 2 127.0.0.1?

medium

A. Two ping requests sent to the local machine with reply times

B. Error: Unknown host 127.0.0.1

C. Ping command runs indefinitely

D. No output, command silently exits

Solution

1. Step 1: Understand the IP address 127.0.0.1

   This IP is the loopback address, meaning the local machine itself.

2. Step 2: Analyze the command with '-c 2'

   The command sends exactly 2 ping requests to the local machine and shows reply times.

3. Final Answer:

   Two ping requests sent to the local machine with reply times -> Option A

4. Quick Check:

   Ping 127.0.0.1 sends replies locally [OK]

Hint: 127.0.0.1 is local machine, ping replies shown [OK]

Common Mistakes:

• Thinking 127.0.0.1 is unreachable
• Expecting infinite ping without -c
• Assuming no output is normal

4. You run ping -c 3 google.com but get the error: ping: unknown option -c. What is the likely cause?

medium

A. You are using a Windows command prompt instead of Linux terminal

B. The domain google.com does not exist

C. You forgot to add the IP address

D. The ping command is missing from your system

Solution

1. Step 1: Understand the error message

   The error says '-c' is unknown, which is not typical in Linux but common in Windows ping.

2. Step 2: Identify environment mismatch

   Windows ping uses '-n' for count, so running Linux-style ping with '-c' in Windows causes this error.

3. Final Answer:

   You are using a Windows command prompt instead of Linux terminal -> Option A

4. Quick Check:

   Windows ping uses -n, Linux uses -c [OK]

Hint: Windows ping uses -n, Linux uses -c [OK]

Common Mistakes:

• Assuming domain name error
• Thinking IP address is mandatory
• Believing ping command is missing

5. You want to write a script that pings a server once and checks if it is reachable. Which command correctly pings 192.168.1.1 once and returns success if reachable?

hard

A. ping -c 1 192.168.1.1; echo 'Server reachable'

B. ping 192.168.1.1 -c 1 || echo 'Server reachable'

C. ping -n 1 192.168.1.1 && echo 'Server reachable'

D. ping -c 1 192.168.1.1 && echo 'Server reachable'

Solution

1. Step 1: Use correct ping syntax for one request

   The -c 1 option sends exactly one ping request in Linux.

2. Step 2: Use logical AND to echo only if ping succeeds

   The && operator runs the echo command only if ping returns success (reachable).

3. Step 3: Analyze other options

   ping 192.168.1.1 -c 1 || echo 'Server reachable' uses || which runs echo on failure, not success. ping -n 1 192.168.1.1 && echo 'Server reachable' uses Windows syntax -n. ping -c 1 192.168.1.1; echo 'Server reachable' always echoes regardless of ping result.

4. Final Answer:

   ping -c 1 192.168.1.1 && echo 'Server reachable' -> Option D

5. Quick Check:

   Use -c 1 and && for success check [OK]

Hint: Use '-c 1' and '&&' to confirm ping success [OK]

Common Mistakes:

• Using Windows ping options in Linux
• Using '||' instead of '&&' for success
• Echoing message regardless of ping result