Network engineers help businesses, and the world, stay connected. They design and implement local area network (LAN) and wide area networks (WAN) to support a connected world, keeping security top of mind as they work. Without network engineers, digital communication would be tedious, and in many cases, not possible.
Because the role is so vital, being prepared for your interview is crucial—companies want to know that you have what it takes to keep their networks operating smoothly with an absolute minimum of issues or downtime. A solid first impression lets hiring managers know you’re qualified; beyond that, you’ll need to show that you have the technical skills to implement, iterate, and evolve networks.
During the job interview process, network engineers can expect a series of questions that range from the technical (such as the tools and techniques you’ve used to build and maintain networks) to the interpersonal (such as how you’ve used “soft skills” like communication and empathy to support your team). Depending on the company and the interviewer, you might also face questions about troubleshooting performance issues, carrying out network monitoring, or configuring security systems such as firewalls. In other words, a network engineer interview often gets very detailed very quickly—you need to be prepared.
But how can you prepare? Let’s explore some possible responses to common network engineer interview questions, and how a few straightforward techniques—such as highlighting your positive impact on your previous employers—can help you stand out in a crowded marketplace.
Understanding Network Engineer Roles
“Network engineers are generally divided into three levels: junior, mid-level, and senior. Juniors handle basic tasks like monitoring and troubleshooting, mid-level engineers design networks and implement security measures, while seniors lead projects and make strategic decisions,” notes Vladislav Bilay, DevOps engineer at Aquiva Labs.
Jacob Kalvo, founder and CEO at Live Proxies, tells Dice: “The three common levels of network engineers are entry-level, mid-level, and senior-level. Entry-level network engineers often handle basic configurations, troubleshooting, and maintenance of network systems, usually with guidance from more experienced colleagues. Mid-level engineers typically take on more complex tasks such as managing larger network infrastructures, configuring advanced security protocols, and mentoring junior engineers. Senior-level network engineers are experts in their field, often responsible for designing and optimizing networks, overseeing security, and making high-level decisions that affect the entire infrastructure.”
Let’s break things down a little more:
Junior Network Engineers
Junior network engineers typically start their careers by focusing on the foundational tasks that keep networks operational. This often involves:
Troubleshooting and Maintenance: Identifying and resolving network issues, such as connectivity problems or slow performance.
- Configuration Management: Setting up and configuring network devices, including routers, switches, and firewalls.
- Monitoring Network Performance: Keeping an eye on network metrics to ensure optimal performance and identify potential problems.
Mid-Level Network Engineers
As network engineers gain experience, their responsibilities expand beyond troubleshooting to include more strategic tasks:
- Network Design and Implementation: Contributing to the design and implementation of new network infrastructure, including selecting hardware and software components.
- Security Management: Implementing and maintaining network security measures to protect against cyber threats.
- Capacity Planning: Ensuring that the network has sufficient capacity to meet future needs.
Senior Network Engineers
Senior network engineers are the architects of complex network infrastructures. They play a pivotal role in:
Strategic Planning: Developing long-term network strategies that align with the organization's business goals.
- Vendor Management: Selecting and managing relationships with network equipment vendors.
- Team Leadership: Mentoring junior network engineers and leading network engineering teams.
- Emerging Technologies: Staying abreast of emerging network technologies and exploring opportunities to leverage them.
At each stage, network engineering certifications could prove critical to candidates who want to stand out in a crowded field of job applicants. Many network engineer job descriptions call for certifications from entities like Cisco or CompTIA. Cisco certifications and CompTIA certifications are industry standard and widely acknowledged as being great indicators of your proficiency.
These two certifications validate your knowledge and understanding of routing, troubleshooting, network security, network protocols, TCP/IP, and DNS—all core competencies hiring managers look for.
As we’re about to see, these certifications and technologies also factor heavily into network engineer job interviews.
Core Network Engineer Interview Questions and How to Answer Them
Network Fundamentals and Protocols
“TCP and UDP are two different protocols. TCP is reliable and connection-oriented, ensuring all data packets arrive correctly, while UDP is faster but less reliable, used when speed is more critical than accuracy, such as in streaming or gaming,” notes Bilay.
DNS translates readable domain names into numerical code machines understand, and is essential for internet communication. Network engineers configure and manage DNS servers, ensuring domains resolve and load efficiently and correctly. DNS is, essentially, the basis for all network interoperability.
While DNS is digital connectivity, network topology addresses the physical ties that bind. This is the actual cords and wires for a network, addressing how computers and servers are actually linked together. There are several types of topologies: bus (devices connected by a single shared cable), star (devices connected to a central hub or switch), ring (devices connected in a circular fashion), and mesh (devices connected to multiple other devices).
These topologies increase in difficulty to implement, which matches the advantages each has. Bus is simplest to implement and has the most limited use-case, while a mesh topology is difficult to implement, fussy to maintain, but offers the greatest advantage to a wider number of users. As needs scale, so does the difficulty of implementing and maintaining network topology.
Router and Routing Protocols
Bilay says: “A router, or gateway, directs data between networks, often connecting a local network to the internet. It determines the best path for data to travel based on factors like destination IP address and network conditions. Hubs, switches, and routers serve different purposes. A hub connects multiple devices but sends data to all, causing inefficiency. A switch is smarter, sending data only to the intended recipient, while a router connects different networks and directs data between them.”
Advanced Network Concepts
Your understanding of advanced concepts will also shine bright in an interview setting. You may be asked about things like VLAN, OSI, subnetting, MAC addresses, and the importance of DHCP and NAT.
OSI (Open Systems Interconnection) is a layered model (physical, data link, network, transport, session, presentation, and application ) defining data transmission across networks. VLANs (Virtual Local Area Networks are divisions of a physical network to support management of traffic. Subnetting divides a network into smaller sub-networks to improve efficiency and security. It’s important to know VLAN and subnetting utilize concepts from the OSI model, so a firm grasp on OSI will carry you a long way.
Where an IP address is a digital identifier that allows computers to communicate with one another, a MAC address is a physical identifier that is rarely changed. A MAC address is used as an identifier for a device.
DHCP assigns IP addresses to devices on a network, which simplifies network management. NAT allows multiple devices on a private network to share a single IP address, which is helpful for improving security and reducing the volume of IP addresses found on a system.
Network Typology
According to DevSkiller CTO Tomasz Nurkiewicz, a few questions in any network engineer interview are likely to focus on the networks you’ve previously worked on. Examples include:
- How were the networks separated from each other?
- How did you organize the network and what kind of topology?
- What were the security measures?
- What were the monitoring and monitoring tools that you use?
The interviewer will also probe how you reacted to common incidents. For example, if employees had connectivity issues or were seeing some strange behavior in the network, how did you respond, and with what tools?
“I wouldn't ask explicitly about a post-mortem, but more along the lines of: How did you make sure this doesn't happen again? Did you did you come up with a procedure and did you document it?” Nurkiewicz added.
An interviewer might also ask about how you arranged coverage during your absences (such as vacation), which shows your capacity for planning. Given the current trends in the network engineering field, you’ll also be asked about your experiences with automation and scripting.
“The days where everything regarding the network infrastructure and network engineering was like fully manual are probably gone,” Nurkiewicz said. “There is a whole movement of having everything in code and setting up networks as like kind of more or less automated and declarative manner.”
Focus on Experience, Highlight Solutions
Nurkiewicz said it’s important to focus on actual experience, such as how you respond under stress or to an incident or security issue. “If there was recently some sort of vulnerability, it’s really great to mention that,” he said. “Perhaps there was some security vulnerability that was extremely influential, some backdoor vulnerability in a popular router.”
Some interviewers may open with a question about a well-known (or just-discovered) vulnerability, just to test the network engineer’s awareness of the industry’s current news. “This tells you whether a candidate has only theoretical knowledge or if they follow the trends and knows what's going on in the wild,” he said.
When asked questions about your past work experiences, it’s important to explain how the decisions you made impacted the organization; for example, if you took the initiative and installed a piece of software that improved the network in some radical (and measurable) way. Or if you developed an innovative approach to filtering messages in order to prevent a malware issue. Such stories illustrate how you know the business needs and can react to those needs using your technical abilities.
“Focus on the way you impacted the company,” Nurkiewicz said. “If you can say you managed to decrease cloud costs by 10 percent because you installed software, that's awesome. If you fixed a bug that was bothering your company for half a year and, and it was just a single line, but no one else found it—that's perfect, because it shows you actually care.”
Prepare for Test Questions on Configuration, Cost Impact
When it comes to the testing portion of the interview, possible tests could vary depending on what the company wants from the candidate. For example, if the company is building out its cloud capabilities, and wants different clouds to talk to one another with a minimal set of privileges, prepare to be tested on that.
Some practical interview questions could include:
- How do you configure power or firewalls?
- How do you configure private networks and VPNs?
- How do you configure kind of bridges between clouds?
- What's the impact of that on costs?
With the aforementioned cloud example, a candidate might have to physically configure a network connection between two clouds or ask the candidate to install a certain firewall or antivirus software.
“As mentioned, they do need to understand what the company needs are and how they can help,” Nurkiewicz said. “Be prepared to prove you understand the choices may make a significant impact on how much the company pays for hardware or cloud costs. This is where the big impact can come from.”
How to Demonstrate Your Value as a Network Engineer
Like most tech jobs, network engineers have to navigate technical prowess with the ability to communicate their work to a non-technical audience. The balance of soft and hard skills is how technologists can best demonstrate their value to hiring managers and ultimately leadership within a company.
Leaders want to know that when problems arise, you will have a firm grasp on how to solve issues quickly, and communicate your findings and work when the time is right. Being able to discuss your experience with network design and optimizing performance in an interview is a great first step.
Further, automation has become a popular topic for hiring managers. They want to know that you can utilize automations to take advantage of your own time to focus on big-picture solutions. This is also why a firm basis in cybersecurity is critical; a lot of time is spent on protecting internal networks.
Preparing for Technical Demonstrations and Problem-Solving Questions
If you’re asked to do a physical demonstration of your experience working with routers, switches, or other physical networking devices, it might be smart to ask the recruiter ahead of time what devices are used at the company. This can give you time to research those devices, and identify how they’re comparable to devices you’ve used in the past.
With networking, hiring managers likely want to know you’ve got hands-on time with hardware and that your knowledge is not simply digital or conceptual.
Be mindful that in an exercise with physical devices, you will likely be expected to solve for a simulated network problem or cybersecurity threat. Brush up on how to handle these situations ahead of your interview.
Conclusion
As network engineers advance in their careers, they should keep in mind that LinkedIn, newsletters, and industry publications are good ways to remain updated on trends within the industry. LinkedIn and Twitter are two good platforms for networking and conversing with other network engineers—remember, networking (in the human sense) is key if you want to find jobs in networking (in the technical sense).
Related Network Engineer Jobs Resources:
How To Become a Network Engineer
