Posted on : 20 May, 2021, 05:01:20 PM

Top 30 Nagios Interview Questions And Answers

Top 30 Nagios Interview Questions And Answers

Nagios is becoming one of the most widely used and popular tools for monitoring continuously. Since several companies and businesses are Since several companies and businesses are now more frequently releasing the software around the world than ever before; so there is a need for dire that can help monitor the software functioning and provide teams relevant and detailed feedback.

Nagios is also one of the ideal reasons that brought monitoring continuously into the picture, making the Nagios tool very important for implementing DevOps. With the rising need for Nagios and Nagios experts, interviews become competitive and tougher. So, Wissenhive decided to help our learning family by putting together all the frequently asked questions from fresher to experienced level questions during the Nagios interview after discussing with industry experts.

1. What do you understand by Nagios?

Refers to one of the best Nagios monitoring tools used for continuous monitoring of applications, business processes, services, and systems, etc., in the culture of DevOps. In the case of a failure, Nagios can alert technical staff about the problem, enabling them to create remediation processes before outages affect company processes, customers, or end-users. With Nagios, an individual doesn’t have to describe why an invisible infrastructure outage affects your business’s bottom line.


2. What are the two different types of states included in Nagios?

The two different types of state included in Nagios are 

  • Soft states
  • Hard states


3. How Nagios helps and supports DevOps experts?

Nagios originated in the primary place to control and monitor applications, infrastructures, and networks. The software automatically has an immediate report and eagle eye in case of failure. It helped in the immediate response of the DevOps expert to follow down and resolve the problem in the very early stages before it can cause any severe damage to the business.


4. What are the uses of Nagios?

  • Nagios works with the server, usually as a service or daemon. 
  • The individual can see the information of the status using the interface of the web.
  • You can also receive SMS or email notifications if something occurs in the system.
  • Nagios frequently runs plugins residing on the same server; they contact servers or hosts on the internet or your network.
  • The Nagios daemon acts similarly as a scheduler that operates specific scripts at certain times.
  • It saves the script's results and will run them on the other scripts if these results improve. Refer to the infographic below:



5. Why is Nagios a perfect tool for continuous monitoring?

  • Automatic fixes the problem
  • Business process 
  • Upgrading infrastructure
  • Infrastructure monitoring
  • Quick acknowledgment to the issues of the system


6. What are some of the databases which support monitoring of Nagios?

There are various databases that support Nagios, and some of them are

  • MySQL
  • Postgres
  • Oracle
  • Microsoft SQL software


7. What do you understand by Plugins in Nagios?

Plugins refer to a script such as Shell scripts, Perl scripts, and so on, which helps in running the command line to check the service or host status. Nagios only utilizes the actual Plugin's results to discover the current status of services and hosts on your network.


8. What is the base language used for the Nagios Core?

PHP+CGI is used for Nagios core, which requires Apache as a webserver to run CGI and PHP.


9. What are some of the Nagios monitoring tools used for Linux mentoring?

When an individual uses the Nagios for monitoring the Linux environment, they are required to understand that they are working with one of the best tools on the planet for monitoring purposes. The entire Nagios package is used for 

  • File system usage
  • Service state
  • Process state
  • System metrics


10. How is Icinga related to the Nagios?

Icinga is also referring to open-source software that is used for monitoring the applications and networks. The main aim of designing Icinga in the first place is to lift up the emergence of Nagios back in the year 2009, but it acts as a monitor software separately.


11. What are the primary or key benefits of using Nagios for monitoring Websites?

  • It improves the availability of the website.
  • It helps in improving the website performance
  • Quickly in detecting online threats such as hijacking and bugs


12. What do you mean by NRPE in Nagios?

The full form of NRPE is Nagios Remote Plugin Executor, designed to allow users to perform Nagios plugins on remote Unix/Linux machines. The core purpose of doing this is to provide Nagios for monitoring local resources such as memory usage, CPU load, and so on. on remote devices or machines.

These public resources are usually not disclosed to external machines, an agent like Nagios Remote Plugin Executor must be connected and installed on the remote Unix/Linux machines.


13. What is OID Nagios?

The OIDs stands for Object IDentifiers that are used to define the detailed information, which is also recognized as Management Information Base or MIBs. The designs are extensible, so businesspeople can define their own objects to be monitored.


14. What is Nagios backend?

Both Logs and Configuration are always stored in a backend. NagiosQL stores configuration in the backend and ndoutils focuses on storing the historical data. In addition, users can also prefer using opdb and nagdb.


15. Can Nagios monitor the window machine?

Yes, users can use Nagios for monitoring the window machine. However, if the users are working with it for the first time, then they should consider following two steps.

  • Setting the Nagios for the monitoring of the window system
  • Add the separate server and host for the monitoring window.


16. What are the different components included in NDO Utilities?

  • FILE2SOCK Utility
  • NDO2DB Daemon
  • NDOMOD Event Broker Module
  • LOG2NDO Utility


17. What do you understand by passive check?

Passive checks are initiated and operated by external processes/applications, and the results of the Passive check are submitted to Nagios for processing. 

Passive checks are valuable and useful for service monitoring that can't be effectively monitored by polling their status on a regularly scheduled basis and Asynchronous in nature. It also monitors the service that cannot be adequately checked by the monitoring hosts and located behind the firewall.

18. Differentiate between Active and Passive Checks

Source Active Checks Passive Checks
Perspective Active from perspective Passive from perspective
Request Initiated Server Client
Server authenticated Client Server
Decides whether to respond and accept the message Client decides Server decides


19. What is Nagios XI?

Currently, Nagios XI refers to one of the most popular and influential monitoring software all around the world market. When there is a need for critical monitoring of infrastructure, experts suggest using and rely on the Nagios XI software. Some of the critical infrastructures are 

  • Applications
  • System metrics
  • Network protocols
  • Services
  • Network protocols


20. What are the key responsibilities of Nagios XI?

  • Comprehensive monitoring
  • Unparalleled performance
  • Multi-Tenant Capabilities
  • Alerting via email 
  • Proactive planning
  • Increased Visibility


21. How does Nagios help with Distributed Monitoring?

With the involvement of Nagios, users can observe and monitor the whole enterprise by utilizing a distributed monitoring scheme in which the instance of Nagios local slave performs two core activities, the reporting of the result and monitoring of tasks. Users can also control all notifications, configuration, and reporting while the slaves are doing all the work from the master.


22. What are the three variables that affect inheritance and recursion in Nagios?

The three main variables are 

  • Name
  • Use
  • Register


23. What is the Nagios Network Analyzer?

A Nagios network analyzer is one of the vital aspects of the software that permits it to do deep scanning of the entire system in search of any potential threat. The reliable and quick scan helps the system admin gather all the necessary data regarding the system’s health and granular data within network analysis.


24. What are some of the virtualization platforms that support Nagios software?

  • Amazon EC2
  • VMware
  • Microsoft Virtual PC
  • Xen


25. What are some of the protocols that support Nagios Software?

The Nagios software supports various protocols, which includes 

  • SMTP Monitoring
  • POP Monitoring
  • FTP Monitoring
  • IPMI Monitoring
  • DNS monitoring
  • LDAP Monitoring


26. Does Nagios refer to object-oriented software?

Nagios software is an object-oriented and open source monitoring software where an individual can design and build the object definitions in the Nagios, which are usually inherited by the other objects. This crucial and important feature of the Nagios further helps in simplifying the complicated connection between components.


27. What port numbers does Nagios use for monitoring their clients?

There are three port numbers that Nagios uses for monitoring their clients.

  • 5666
  • 5667
  • 5668


28. How does Flap Detection work in the Nagios software?

Nagios software helps in supporting optional detection services and the host that are known as flapping. The situation of flapping in Nagios happens when a host or service changes their state too frequently, which results in a problem storm and recovery notifications. Flapping can be easily indicative of real network problems or configuration problems.


29. What are the different objects types that individuals can witness in Nagios?

There are six different types of object that a user can witness in Nagios are 

  • Hosts
  • Contact
  • Services
  • Host groups
  • Time periods
  • Commands
  • Notification escalations


30. Explain State Stalking 

State Stalking is a term used for logging purposes. When Stalking is approved for a particular service or host, Nagios starts watching that service or host very thoroughly and logs any modifications it detects in the output of checked results.


Here, Wissenhive covered the top 30 Nagios interview questions with answers from beginner to advanced level to give the candidate a strong idea about interview questions that they might encounter during the interview.

If you find this article helpful and looking for some platform to learn or enhance the Nagios skills from industry professionals, then enroll yourself in a Nagios Certified Professional Course. Let us know your query and doubts in the comment box on the Nagios interview questions if any, and we will get back to you within 24 hours.

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