ping for connectivity testing in Linux CLI - Mini Project: Build & Apply

Ping for Connectivity Testing

📖 Scenario: You are a network technician who needs to check if certain devices on your network are reachable. You will use the ping command to test connectivity to these devices.

🎯 Goal: Build a simple script that stores a list of IP addresses, sets a count for ping attempts, runs the ping command on each IP, and displays the results.

📋 What You'll Learn

Create a list of IP addresses to test

Set a variable for the number of ping attempts

Use a loop to ping each IP address the set number of times

Display the ping results for each IP

💡 Why This Matters

🌍 Real World

Network administrators often need to check if devices are reachable to troubleshoot connectivity issues.

💼 Career

Knowing how to automate ping tests helps in monitoring network health and diagnosing problems quickly.

1

Create the list of IP addresses

Create a variable called ip_addresses that is a list containing these exact IP addresses as strings: '8.8.8.8', '8.8.4.4', and '1.1.1.1'.

Linux CLI

# Create the list of IP addresses
# Your code here

Hint

Use parentheses to create a list of strings in bash.

2

Set the ping count variable

Create a variable called ping_count and set it to 3 to specify the number of ping attempts per IP.

Linux CLI

ip_addresses=('8.8.8.8' '8.8.4.4' '1.1.1.1')
# Set the ping count variable
# Your code here

Hint

Assign the number 3 to the variable ping_count without spaces around the equals sign.

3

Ping each IP address

Use a for loop with the variable ip to iterate over ip_addresses. Inside the loop, run the command ping -c $ping_count $ip to ping each IP the set number of times.

Linux CLI

ip_addresses=('8.8.8.8' '8.8.4.4' '1.1.1.1')
ping_count=3
# Use a for loop to ping each IP
# Your code here

Hint

Use "${ip_addresses[@]}" to loop over all IPs in the list.

4

Display the ping results

Add a echo statement inside the loop to print "Pinging $ip:" before running the ping command. This will label the output for each IP address.

Linux CLI

ip_addresses=('8.8.8.8' '8.8.4.4' '1.1.1.1')
ping_count=3
for ip in "${ip_addresses[@]}"
do
    # Print label before ping
    # Your code here
    ping -c $ping_count $ip
    echo "---"
done

Hint

Use echo "Pinging $ip:" to show which IP is being pinged.

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