Network monitoring script in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of ping command in a monitoring script

What is the output of this command snippet when the host is reachable?

Bash Scripting

ping -c 1 8.8.8.8 | grep '1 packets transmitted' | awk '{print $4, "received"}'

A 0 received

B 1 packets transmitted

C 1 received

D Destination Host Unreachable

💡 Hint

Look for the part of the ping output that shows how many packets were received.

The command filters the ping output to show the number of packets received. When the host is reachable, it shows '1 received'.

❓ Configuration

intermediate

Correct crontab entry for running a network check every 5 minutes

Which crontab entry correctly runs a script located at /usr/local/bin/netcheck.sh every 5 minutes?

A 5 * * * * /usr/local/bin/netcheck.sh

B */5 * * * * /usr/local/bin/netcheck.sh

C 0 5 * * * /usr/local/bin/netcheck.sh

D * * 5 * * /usr/local/bin/netcheck.sh

💡 Hint

The first field controls minutes and '*/5' means every 5 minutes.

The crontab syntax '*/5 * * * *' runs the command every 5 minutes.

❓ Troubleshoot

advanced

Why does this network monitoring script fail to detect downtime?

Given this script snippet: #!/bin/bash ping -c 1 192.168.1.1 if [ $? -eq 0 ]; then echo "Host is up" else echo "Host is down" fi Why might it fail to detect downtime correctly?

Bash Scripting

#!/bin/bash
ping -c 1 192.168.1.1
if [ $? -eq 0 ]; then
  echo "Host is up"
else
  echo "Host is down"
fi

A The ping command may succeed but the host could still be unreachable due to firewall.

B The script does not redirect ping output, so errors are missed.

C The script checks the exit status immediately, but ping may take time to respond.

D The script uses $? incorrectly; it should check the output string instead.

💡 Hint

Consider network conditions beyond ping success.

Ping may succeed if ICMP packets are allowed, but the host might still be unreachable for other services due to firewall or routing issues.

🔀 Workflow

advanced

Order the steps to create a basic network monitoring script

Put these steps in the correct order to create a simple network monitoring script that alerts on downtime.

A 1,2,3,4

B 2,1,3,4

C 1,3,2,4

D 3,1,2,4

💡 Hint

Think about the logical flow from script creation to scheduling.

First write the ping script, then check its result, send alert if needed, and finally schedule it.

✅ Best Practice

expert

Best practice for handling false positives in network monitoring scripts

Which approach best reduces false positives when a network monitoring script detects downtime?

A Ignore ping failures and rely on manual checks.

B Alert immediately on the first failed ping attempt.

C Increase the ping timeout to a very high value.

D Run multiple ping attempts and alert only if all fail.

💡 Hint

Think about confirming failure before alerting.

Multiple attempts reduce false alarms caused by transient network issues.