30 Interview questions to ask while hiring a network engineer

In today’s digital-first world, the role of a network engineer is more critical than ever. According to a recent report by Gartner, 87% of organizations are accelerating their digital transformation initiatives, highlighting the growing reliance on robust network infrastructures.

Furthermore, the U.S. Bureau of Labor Statistics projects a 6% growth in network and computer systems administrators’ jobs from 2020 to 2030, underscoring the increasing demand for skilled network engineers. As HR leaders and CXOs, identifying the right talent is pivotal. By asking the right interview questions, you can ensure that candidates have the technical proficiency and align with your company’s strategic goals. In this blog, we will explore key questions that can help you make informed hiring decisions and secure top-tier network engineering talent for your organization. 

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Why use skills assessments for assessing network engineer candidates?

Skills assessments play a vital role in the hiring process in the competitive network engineering field. Utilizing platforms like Testlify allows HR professionals and CXOs to evaluate candidates’ technical abilities objectively. These assessments cover essential areas such as coding skills and knowledge of various networking protocols and tools. By incorporating skills assessments, you can ensure that candidates possess the theoretical knowledge and the practical expertise necessary for the role. This approach leads to more informed hiring decisions, ensuring your network engineering team is equipped with top-tier talent.

When should you ask these questions in the hiring process?

The ideal way to incorporate Network Engineer interview questions in the hiring process is to invite applicants to complete a skills assessment tailored to the role. This initial step helps screen candidates for their technical proficiency and understanding of key networking concepts. Following the evaluation, you can use targeted interview questions to delve deeper into their practical experience, problem-solving abilities, and alignment with your company’s needs. This structured approach ensures that only the most qualified candidates move forward, saving time and resources while enhancing the quality of your hires.

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General network engineer interview questions to ask applicants

When hiring a Network Engineer, asking the right technical questions is essential to evaluate the candidate’s expertise and suitability for your organization. To comprehensively assess the candidate’s skills and knowledge, these questions should cover various topics, including network fundamentals, protocols, troubleshooting, and security. Below are 25 technical questions with what to expect in the answers and what to look for in the candidate’s responses.

1. Explain the OSI model and its layers.

Look for: Deep understanding of each layer, practical examples, and how the layers interact.

What to expect: A detailed explanation of the seven layers (Physical, Data Link, Network, Transport, Session, Presentation, and Application), including examples of protocols and functions for each layer.

2. What is the difference between TCP and UDP?

Look for: Clear differentiation, examples of when to use each protocol, understanding of their benefits and drawbacks.

What to expect: Description of TCP as connection-oriented and reliable and UDP as connectionless and faster, including use cases for each.

3. How does subnetting work, and why is it used?

Look for: Accurate calculations, practical applications, understanding of subnet masks and CIDR notation.

What to expect: Explanation of dividing a network into smaller sub-networks, how to calculate subnets, and the benefits such as improved performance and security.

4. Describe how a VPN works.

Look for: Understanding of security implications, practical examples of usage, and familiarity with configuration.

What to expect: Overview of VPN types (site-to-site, remote access), encryption methods, and tunneling protocols (e.g., PPTP, L2TP, IPsec).

5. What is NAT, and how does it work?

Look for: Examples of NAT usage, understanding of translation tables, benefits, and limitations.

What to expect: Explanation of Network Address Translation, its purpose in conserving IP addresses, and types (static, dynamic, PAT).

6. Explain the difference between a switch and a router.

Look for: Clear distinctions, practical examples, and knowledge of specific protocols (e.g., STP for switches, OSPF for routers).

What to expect: Differences in function (switches operate at Layer 2, routers at Layer 3), use cases, and how each device manages traffic.

7. What is DNS, and how does it work?

Look for: Understanding of DNS records, zone files, and common issues (e.g., propagation delays).

What to expect: Description of the Domain Name System, its hierarchical structure, and processes like resolution and caching.

8. How do you secure a network?

Look for: Comprehensive security measures, practical experience, and an understanding of best practices.

What to expect: Strategies including firewalls, encryption, VPNs, intrusion detection/prevention systems, and regular updates.

9. What is a VLAN and why is it used?

Look for: Practical examples, configuration methods, and understanding of VLAN tagging.

What to expect: Explanation of Virtual LANs, their purpose in segmenting network traffic, and benefits such as improved security and reduced congestion.

10. Describe BGP and its importance in networking.

Look for: Knowledge of BGP attributes, real-world applications, and potential issues.

What to expect: Overview of Border Gateway Protocol, its role in routing between autonomous systems, and key concepts like path selection.

11. What are the different types of wireless encryption?

Look for: Understanding of encryption methods, practical examples of configuration, and awareness of security implications.

What to expect: Comparison of WEP, WPA, WPA2, and WPA3, including their strengths, weaknesses, and use cases.

12. How do you troubleshoot network connectivity issues?

Look for: Logical problem-solving process, experience with common tools, and practical examples.

What to expect: Systematic approach including checking physical connections, using diagnostic tools (ping, traceroute), and examining configurations.

13. What is QoS, and why is it important?

Look for: Practical applications, configuration examples, and understanding of QoS policies.

What to expect: Explanation of Quality of Service, its role in managing bandwidth, and methods like traffic shaping and prioritization.

14. Describe the process of setting up a wireless network.

Look for: Detailed process, practical experience, and awareness of potential challenges.

What to expect: Steps including site survey, selecting equipment, configuring SSIDs and encryption, and ensuring coverage and performance.

15. What is MPLS, and how does it work?

Look for: Understanding of MPLS benefits, practical examples, and configuration knowledge.

What to expect: Overview of Multiprotocol Label Switching, its purpose in improving data flow efficiency, and key concepts like labels and LSPs.

16. Explain the function of a firewall and types available.

Look for: Practical examples, understanding of firewall rules, and experience with specific products.

What to expect: Description of firewall types (packet-filtering, stateful, proxy), their functions, and configuration basics.

17. How does network redundancy work?

Look for: Examples of redundancy implementation, understanding of failover processes, and practical experience.

What to expect: Explanation of redundant paths, protocols like HSRP and VRRP, and benefits in ensuring network availability.

18. What is SNMP, and how is it used?

Look for: Practical examples, familiarity with SNMP versions, and configuration experience.

What to expect: Overview of Simple Network Management Protocol, its role in monitoring and managing network devices, and key concepts like MIBs.

19. Describe how IPv6 differs from IPv4.

Look for: Detailed understanding, examples of IPv6 implementation, and transition strategies.

What to expect: Key differences include address format, header structure, and improvements in IPv6, like simplified routing.

20. What is an IDS/IPS and how does it work?

Look for: Practical examples, configuration knowledge, and understanding of deployment scenarios.

What to expect: Explanation of Intrusion Detection/Prevention Systems, their roles in network security, and methods of detection (signature-based, anomaly-based).

21. How do you configure network devices using CLI?

Look for: Practical experience, familiarity with CLI environments, and examples of configurations.

What to expect: Steps for configuring routers, switches, and other devices using Command Line Interface, including common commands.

22. What is network segmentation, and why is it important?

Look for: Practical examples, understanding of benefits, and configuration knowledge.

What to expect: Explanation of dividing a network into smaller segments to improve security and performance, and methods like VLANs and firewalls.

23. Describe the importance of network monitoring.

Look for: Practical experience with monitoring tools, metrics understanding, and issue resolution examples.

What to expect: Role of monitoring in maintaining network health, tools used (e.g., Nagios, SolarWinds), and key metrics to track.

24. What is the role of a DHCP server in a network?

Look for: Understanding of DHCP process, practical examples, and troubleshooting experience.

What to expect: Explanation of Dynamic Host Configuration Protocol, its function in assigning IP addresses, and configuration steps.

25. How do you handle network security incidents?

Look for: Detailed incident handling process, practical experience, and an understanding of best practices.

What to expect: Steps including identification, containment, eradication, and recovery, along with examples of incidents handled.

Interview questions to gauge a candidate’s experience level

26. Can you describe a challenging network issue you faced and how you resolved it?

27. How do you prioritize and manage multiple network projects simultaneously?

28. Describe when you had to explain a complex technical issue to a non-technical stakeholder. How did you ensure they understood?

29. Can you provide an example of how you’ve contributed to improving network security in your previous roles?

30. How do you stay updated with the latest networking technologies and industry trends?

Key takeaways 

Hiring the right Network Engineer is crucial for maintaining a robust and secure network infrastructure in today’s rapidly evolving digital landscape. By combining Network Engineer test with targeted interview questions, organizations can ensure candidates possess both the technical expertise and the practical experience required for the role. Platforms like Testlify offer valuable tools to objectively evaluate coding skills and knowledge of essential networking concepts.

Additionally, incorporating questions to assess soft skills and past experiences allows hiring managers to gauge a candidate’s problem-solving abilities, communication skills, and adaptability. This comprehensive approach to interviewing helps secure top-tier talent capable of driving your organization’s network performance and security to new heights.

Stay Informed: Want precision hiring? Check out our Ultimate Guide to Hiring a Top-Notch Network Engineer.