Nagios Hands-On Troubleshooting
Evaluation Exam Practice Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. What is the first step when Nagios services are not starting?
A. Restart Apache
B. Check configuration files
C. Delete logs
D. Reinstall Nagios
Answer: B) Check configuration files
Rationale: Configuration errors are the most common cause of
startup failures and should be validated first using nagios -v.
2. Which command verifies Nagios configuration?
A. nagios -t
B. nagios -v
C. nagios -c
, D. nagios --check
Answer: B) nagios -v
Rationale: The -v flag validates configuration syntax before service
restart.
3. If Nagios web interface is not loading, what should you check first?
A. Database service
B. Apache service
C. SMTP service
D. SSH service
Answer: B) Apache service
Rationale: Nagios XI/Core UI depends on Apache or HTTP server
being active.
4. Which file defines host and service definitions?
A. commands.cfg
B. nagios.cfg
C. objects configuration files
D. resource.cfg
Answer: C) objects configuration files
Rationale: Hosts and services are defined in object definition files.
5. What does a "CRITICAL" status indicate?
A. Service is unreachable
B. Service is functioning normally
, C. Service has failed or is in bad state
D. Service is restarting
Answer: C) Service has failed or is in bad state
Rationale: CRITICAL means service has exceeded threshold or failed
health check.
6. Which log file is most useful for troubleshooting Nagios issues?
A. /var/log/messages
B. nagios.log
C. apache.log
D. syslog.conf
Answer: B) nagios.log
Rationale: Nagios log contains service check results and errors.
7. What daemon runs Nagios monitoring engine?
A. httpd
B. nagios
C. nrpe
D. sshd
Answer: B) nagios
Rationale: The nagios daemon performs monitoring checks.
8. Which command restarts Nagios service?
A. service nagios restart
B. systemctl reload nagios
, C. restart nagiosd
D. nagios restart
Answer: A) service nagios restart
Rationale: Standard service management command restarts Nagios
daemon.
9. If passive checks are not updating, what should you verify?
A. Disk space
B. External command file permissions
C. DNS settings
D. CPU usage
Answer: B) External command file permissions
Rationale: Passive checks rely on external command file (/cmd.cgi or
pipe).
10. Which file controls Nagios core settings?
A. commands.cfg
B. nagios.cfg
C. hosts.cfg
D. services.cfg
Answer: B) nagios.cfg
Rationale: Core configuration file controls global Nagios behavior.
11. What is NRPE used for?
A. Web interface
Evaluation Exam Practice Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the first step when Nagios services are not starting?
A. Restart Apache
B. Check configuration files
C. Delete logs
D. Reinstall Nagios
Answer: B) Check configuration files
Rationale: Configuration errors are the most common cause of
startup failures and should be validated first using nagios -v.
2. Which command verifies Nagios configuration?
A. nagios -t
B. nagios -v
C. nagios -c
, D. nagios --check
Answer: B) nagios -v
Rationale: The -v flag validates configuration syntax before service
restart.
3. If Nagios web interface is not loading, what should you check first?
A. Database service
B. Apache service
C. SMTP service
D. SSH service
Answer: B) Apache service
Rationale: Nagios XI/Core UI depends on Apache or HTTP server
being active.
4. Which file defines host and service definitions?
A. commands.cfg
B. nagios.cfg
C. objects configuration files
D. resource.cfg
Answer: C) objects configuration files
Rationale: Hosts and services are defined in object definition files.
5. What does a "CRITICAL" status indicate?
A. Service is unreachable
B. Service is functioning normally
, C. Service has failed or is in bad state
D. Service is restarting
Answer: C) Service has failed or is in bad state
Rationale: CRITICAL means service has exceeded threshold or failed
health check.
6. Which log file is most useful for troubleshooting Nagios issues?
A. /var/log/messages
B. nagios.log
C. apache.log
D. syslog.conf
Answer: B) nagios.log
Rationale: Nagios log contains service check results and errors.
7. What daemon runs Nagios monitoring engine?
A. httpd
B. nagios
C. nrpe
D. sshd
Answer: B) nagios
Rationale: The nagios daemon performs monitoring checks.
8. Which command restarts Nagios service?
A. service nagios restart
B. systemctl reload nagios
, C. restart nagiosd
D. nagios restart
Answer: A) service nagios restart
Rationale: Standard service management command restarts Nagios
daemon.
9. If passive checks are not updating, what should you verify?
A. Disk space
B. External command file permissions
C. DNS settings
D. CPU usage
Answer: B) External command file permissions
Rationale: Passive checks rely on external command file (/cmd.cgi or
pipe).
10. Which file controls Nagios core settings?
A. commands.cfg
B. nagios.cfg
C. hosts.cfg
D. services.cfg
Answer: B) nagios.cfg
Rationale: Core configuration file controls global Nagios behavior.
11. What is NRPE used for?
A. Web interface
