Network Engineer Interview Questions

You’ve studied the OSI model. You can subnet in your head. You’ve labbed OSPF configurations until your eyes glazed over.

And now you’re sitting across from a hiring manager who asks: “Tell me about a time you had to explain a complex network issue to a non-technical stakeholder.”

Technical knowledge gets you in the door. But networking interviews in 2026 test more than your ability to recite protocol definitions. Hiring managers want to see how you think, how you troubleshoot, and whether you can communicate without hiding behind jargon.

This guide covers the questions that actually come up—from fundamental technical concepts to behavioral scenarios—and shows you how to answer them in ways that make interviewers want to hire you.

What Network Engineering Interviews Really Test

Before diving into specific questions, understand what’s actually being evaluated. Interviews for network roles typically assess five areas:

Technical fundamentals: Can you explain core networking concepts clearly? Not just memorize them—explain them to someone who might not be technical.

Troubleshooting methodology: When something breaks at 2 AM, do you panic or follow a systematic approach?

Current relevance: Networks aren’t just routers and switches anymore. Interviewers want to know you understand cloud networking, automation, and security.

Communication: The best network engineer is useless if they can’t explain why a migration needs to happen or document their work.

Cultural fit: Will you work well with the team? Blame vendors when things go wrong? Hoard knowledge or share it?

Keep these in mind as you read through the questions. The “right” answer isn’t always the most technically complete—it’s the one that demonstrates these qualities.

Fundamental Technical Questions

These form the baseline. If you stumble here, the interview probably won’t go further.

”Explain the OSI model and why it matters”

Everyone asks this. Not because it’s the most practical knowledge, but because your answer reveals whether you understand networking conceptually or just memorized facts for a certification.

Strong answer approach: Don’t recite all seven layers. Instead, explain why the model exists (standardization, troubleshooting framework, vendor interoperability) and give a practical example.

“The OSI model gives us a common language for troubleshooting. When someone says ‘it’s a Layer 2 issue,’ we immediately know to check MAC addresses, VLANs, and switch configurations rather than looking at IP routing. In practice, I use it as a troubleshooting checklist—if pings work but HTTP doesn’t, I’m not wasting time at Layer 1.”

What interviewers actually want to hear: That you understand the model as a tool, not just academic theory. Bonus points if you mention the TCP/IP model and when you’d use one framework over the other.

”What’s the difference between TCP and UDP?”

Another fundamental, but your answer reveals depth of understanding.

Surface-level answer (what most candidates say): “TCP is connection-oriented and reliable, UDP is connectionless and faster.”

Better answer: “TCP establishes a three-way handshake before transmitting and guarantees delivery through acknowledgments and retransmission. UDP fires and forgets—no handshake, no delivery confirmation. I choose TCP for anything where data integrity matters: file transfers, web traffic, email. UDP makes sense when speed trumps reliability and the application handles error correction: VoIP, video streaming, DNS queries.”

Even better: Mention a real scenario where you chose one over the other, or troubleshot an issue caused by choosing wrong. For more on structuring technical responses, see our guide on technical interview preparation.

”Walk me through subnetting”

If you’re interviewing for network roles, you need to subnet confidently. Fumbling here raises serious red flags.

What they’re testing: Mental math ability, understanding of CIDR notation, and whether you can explain your reasoning.

Good approach: Work through a specific example out loud. “If I need to subnet 192.168.1.0/24 into four equal networks, I need two additional bits for the network portion—that gives me /26 subnets with 62 usable hosts each. The subnets would be 192.168.1.0/26, 192.168.1.64/26, 192.168.1.128/26, and 192.168.1.192/26.”

Practice until this is automatic. There are plenty of free subnetting calculators online, but in an interview, you need to work through the logic yourself. Our guide on DHCP fundamentals covers related concepts that often come up alongside subnetting questions.

”Explain VLANs and when you’d use them”

VLANs are fundamental to any enterprise network. Expect follow-up questions about trunking, native VLANs, and inter-VLAN routing.

Strong answer: “VLANs segment a physical network into logical broadcast domains. I’d use them to separate traffic by function—putting voice, data, and management on different VLANs improves security and reduces broadcast noise. Between switches, I’d use 802.1Q trunks to carry tagged traffic. If devices on different VLANs need to communicate, I’d configure inter-VLAN routing through a Layer 3 switch or router-on-a-stick setup.”

Follow-up they might ask: “What’s a native VLAN and why does it matter for security?” (Untagged traffic defaults to the native VLAN—if left at default VLAN 1, it’s a security risk. Always change it and disable unused ports.)

If you’re still building your networking foundation, our networking basics guide covers the fundamentals interviewers expect you to know.

Routing Protocol Questions

Expect at least one deep dive into routing. The specific protocol depends on the environment, but these questions test your understanding of how routing works.

”Compare OSPF and EIGRP”

This question assesses whether you understand routing protocols beyond memorized facts.

Aspect	OSPF	EIGRP
Type	Link-state	Advanced distance-vector
Standard	Open (IETF)	Cisco proprietary (now open)
Metric	Cost (bandwidth)	Composite (bandwidth, delay, etc.)
Convergence	Fast with areas designed properly	Very fast with feasible successors
Complexity	Higher (areas, LSA types)	Lower for basic deployments
Best for	Multi-vendor, large enterprises	Cisco-dominant environments

What to emphasize: Your choice depends on the environment. OSPF makes sense in multi-vendor networks or when you need standards compliance. EIGRP converges faster and is simpler to configure in all-Cisco shops.

If you’re preparing for your CCNA certification, you’ll need deep familiarity with both protocols.

”What’s administrative distance and why does it matter?”

This tests whether you understand how routers make decisions when multiple routing sources exist.

Answer: “Administrative distance is a trustworthiness rating for routing sources. If a router learns about the same destination from OSPF (AD 110) and EIGRP (AD 90), it installs the EIGRP route because lower AD means more trusted. This matters when running multiple routing protocols or during migrations—you need to understand which route wins.”

Practical example to add: “I’ve used AD manipulation during cutovers. Setting a temporarily higher AD on backup routes lets you control which path traffic takes during maintenance windows."

"How would you troubleshoot a routing issue where packets reach halfway to the destination?”

This is a practical troubleshooting question that reveals your methodology.

Strong approach:

1. “First, I’d verify the topology—traceroute to identify where packets stop.”
2. “Check the routing table on the last hop that works. Is there a route to the destination?”
3. “If the route exists but traffic drops, check for asymmetric routing. The return path might be broken.”
4. “Look for ACLs or firewall rules that might block traffic in one direction.”
5. “Check interface states—a flapping link could cause intermittent reachability.”

The key is demonstrating a systematic approach rather than random guessing. Our DNS troubleshooting guide covers similar methodical approaches to network problems.

Security Questions

Network security has become non-negotiable. Even if you’re not applying for a security role, expect questions about securing the infrastructure you manage.

”How would you secure a network switch?”

This tests practical security knowledge, not theoretical concepts.

Strong answer:

• “Disable unused ports and assign them to a black hole VLAN”
• “Enable port security to limit MAC addresses per port”
• “Configure 802.1X for authentication where supported”
• “Disable CDP on edge ports facing untrusted devices”
• “Change the native VLAN from default and disable VLAN 1 where possible”
• “Enable DHCP snooping to prevent rogue DHCP servers”
• “Configure dynamic ARP inspection to prevent ARP spoofing”
• “Use SSH instead of Telnet, and disable HTTP management”

What makes this answer strong: It covers multiple layers of defense and shows you think about security holistically, not just checking a compliance box.

The ability to explain technical concepts to non-technical people is just as important as knowing the technical details.

”Explain the difference between a firewall and an ACL”

Another question that seems basic but reveals understanding depth.

Good answer: “ACLs filter traffic based on source, destination, and port information—they’re stateless and examine each packet individually. Firewalls are stateful; they track connections and make decisions based on traffic patterns, not just individual packets. ACLs work well for simple permit/deny rules, but firewalls can do application inspection, threat detection, and complex rule logic that ACLs can’t handle.”

For those transitioning toward security specializations, our cybersecurity career transition guide covers how networking skills translate.

”What’s the purpose of a DMZ?”

Answer: “A DMZ creates a buffer zone between the untrusted internet and the trusted internal network. Public-facing servers—web servers, mail servers, VPN concentrators—live in the DMZ. If they get compromised, attackers still face another firewall before reaching internal resources. Traffic flows are restricted: internet can reach the DMZ, DMZ can reach limited internal resources, but the internet can’t reach the internal network directly.”

Automation and Modern Infrastructure

Network engineering in 2026 requires more than CLI skills. Interviewers want to know you can work with automation, cloud networking, and software-defined approaches.

”What experience do you have with network automation?”

If your answer is “none,” that’s a problem. At minimum, demonstrate awareness of the direction the field is moving.

Honest but positive answer if you’re learning: “I’ve started using Ansible for configuration management—pushing standardized configs to switches and automating backup tasks. I’ve also written Python scripts for parsing show commands and generating reports. I’m working toward network programmability skills because I know that’s where the industry is heading.”

If you have experience: Be specific. “In my last role, I used Ansible to deploy a standardized NTP, syslog, and SNMP configuration across 200 switches. What used to take a week of manual work now runs in 20 minutes with full version control in Git.”

For hands-on practice, Shell Samurai offers interactive terminal exercises that build the scripting fundamentals automation requires.

”How does SD-WAN differ from traditional WAN?”

SD-WAN questions are increasingly common as organizations move away from MPLS.

Answer: “Traditional WAN relies on dedicated circuits like MPLS with hardware-defined routing decisions. SD-WAN abstracts the control plane from the physical transport—you can use MPLS, broadband, LTE, whatever’s available. The controller makes intelligent routing decisions based on application requirements and current path quality. Benefits include cost savings from using cheaper internet links, simplified management through centralized policy, and better application performance through dynamic path selection."

"Have you worked with cloud networking? AWS, Azure, GCP?”

Even if the role isn’t cloud-focused, understanding how networks extend into cloud environments is expected.

Good approach: “I’ve worked with AWS VPCs—setting up subnets, route tables, security groups, and NACLs. The concepts translate from on-prem networking, but the abstraction layer changes how you implement them. Instead of configuring switch ports, you’re defining rules in the console or through Terraform. I’ve also set up VPN connections between on-prem data centers and AWS VPCs.”

If you haven’t done this in production, mention labbing: “I’ve set up multi-region VPC peering in my home lab to understand traffic flow and cost implications.”

Home labs are a huge differentiator. If you’re highlighting yours in interviews, see our guide on how to showcase homelab projects on your resume.

Behavioral and Situational Questions

Technical skills get you shortlisted. Behavioral questions determine whether you get hired.

”Tell me about a time you troubleshot a major network outage”

This is your chance to demonstrate troubleshooting methodology under pressure.

STAR method structure (Situation, Task, Action, Result):

• Situation: “We had a complete loss of connectivity affecting 500 users during peak business hours.”
• Task: “As the on-call engineer, I needed to identify and resolve the issue as quickly as possible while keeping stakeholders informed.”
• Action: “I started at Layer 1—verified physical connections and link lights. Discovered a core switch had failed. While the hardware team arranged replacement, I worked around it by recabling through a backup switch. Documented the workaround so the next shift knew the situation.”
• Result: “Service was restored in 45 minutes. The post-incident review led to implementing redundant core switching, which has prevented similar single points of failure.”

For more on structuring behavioral answers, see our STAR method interview guide.

”Describe a time you disagreed with a colleague about a technical approach”

This tests conflict resolution and communication skills.

What they want to hear: That you can disagree professionally, present evidence for your position, and ultimately support the team decision whether or not you “won.”

Weak answer: “I was right and eventually they realized it.”

Strong answer: “A colleague wanted to implement EIGRP for a new site, but we had non-Cisco switches in the path. I advocated for OSPF for interoperability. We brought both perspectives to the team lead, I presented the vendor compatibility concerns, and we went with OSPF. What mattered was that we made the decision together based on facts, not egos."

"How do you stay current with networking technology?”

This question assesses whether you’ll become obsolete or continue growing.

Good answers include:

• “I maintain a home lab with GNS3/EVE-NG where I test new configurations before proposing them at work”
• “I follow NetworkChuck, David Bombal, and the Packet Pushers podcast for industry trends”
• “I’m working toward my CCNP because I want deeper understanding of enterprise routing and switching”
• “I participate in the r/networking subreddit and help answer questions—teaching reinforces my own understanding”

What they don’t want to hear: “I got my CCNA five years ago and haven’t studied since.”

Our guide on how to become a network engineer covers continuous learning paths in more detail. If you’re wondering whether certifications are worth pursuing, we break down the certification vs experience debate.

”Tell me about a mistake you made and how you handled it”

Every experienced engineer has stories. The question tests self-awareness and learning.

Strong answer structure:

1. Own the mistake completely (no excuses or blame)
2. Explain the impact honestly
3. Describe what you did to fix it
4. Share what you learned and changed

Example: “Early in my career, I fat-fingered a route while making a change during business hours instead of waiting for the maintenance window I’d been granted. Took down connectivity for a finance team for 20 minutes. I immediately owned the mistake to my manager, documented exactly what happened, and implemented a personal checklist for config changes that I still use today. Never made that specific mistake again.”

Questions You Should Ask

Interviews are bidirectional. Asking good questions demonstrates engagement and helps you evaluate whether the role fits.

Technical environment questions

• “What does your network monitoring stack look like?”
• “How do you handle change management? Is there a formal CAB process?”
• “What’s your automation maturity level? Are you using any orchestration tools?”
• “Is there on-call rotation? What does coverage look like?”

Team and culture questions

• “How is the team structured? Who would I work most closely with?”
• “What does success look like in the first 90 days?”
• “What’s the biggest challenge the network team is facing right now?”
• “How do you handle professional development? Is there budget for training and certifications?”

Career growth questions

• “What does the career path look like for network engineers here?”
• “Are there opportunities to work on projects outside day-to-day operations?”

Common Interview Mistakes to Avoid

After reviewing hundreds of interview outcomes, these patterns consistently derail candidates:

Talking in acronyms without explaining: Dropping “BGP,” “MPLS,” and “SD-WAN” without context makes interviewers question whether you actually understand these technologies or just know the terms.

Inability to admit “I don’t know”: Nobody knows everything. “I haven’t worked with that specific technology, but here’s how I’d approach learning it” is far better than making something up.

Blaming others for past failures: Even if your previous employer had terrible processes, complaining about them raises red flags about accountability.

Focusing only on technical skills: Communication, documentation, and teamwork matter as much as technical knowledge. Demonstrate both.

Not asking questions: It signals either lack of interest or lack of critical thinking about whether the role is right for you.

For more pitfalls, see our full guide on IT job interview mistakes.

Preparation Checklist

Two weeks before:

• Review fundamental concepts (OSI model, TCP/IP, subnetting)
• Refresh knowledge on routing protocols relevant to the job description
• Update your resume with quantifiable achievements
• Research the company’s technology stack if possible
• Ensure your resume highlights networking accomplishments with quantifiable metrics

One week before:

• Practice explaining technical concepts out loud (record yourself)
• Prepare 3-4 STAR stories covering troubleshooting, conflict, and mistakes
• Review the job description and match your experience to each requirement
• Prepare thoughtful questions for the interviewers

Day before:

• Test video/audio if it’s a remote interview
• Have a copy of your resume readily available
• Get solid sleep—technical questions require clear thinking

Day of:

• Arrive early or log in 5 minutes before virtual interviews
• Have water available (you’ll be talking a lot)
• Take a breath before answering—thinking before speaking shows confidence

What Happens After

If you don’t hear back within the timeframe they gave, following up once is appropriate. More than that gets pushy.

If you don’t get the offer, ask for feedback. Not everyone provides it, but when they do, it’s valuable for future interviews.

If you get the offer, negotiate. Network engineers are in demand—according to The Interview Guys, salaries range from $95,000 to over $120,000 depending on experience and location. Don’t leave money on the table. Our salary negotiation guide covers specific tactics.

FAQ

How technical should I get in my answers?

Match the interviewer’s level. If they’re a hiring manager, keep explanations accessible. If it’s a senior engineer, you can go deeper. Watch for cues—if eyes glaze over, simplify.

What if I don’t have my CCNA yet?

Many network roles don’t require certifications, especially at the junior level. Focus on demonstrating knowledge through project examples, home lab work, and clear explanations. Mention that you’re actively studying if true. If you’re wondering whether the CCNA makes sense for you, our complete CCNA analysis breaks down the ROI by career path.

Should I bring notes to reference?

For technical interviews, having a notepad is fine and even expected—it shows preparation. Just don’t read answers verbatim; use notes as reference points.

How do I handle questions about technology I haven’t used?

Be honest: “I haven’t worked directly with [technology], but I understand the concepts. It’s similar to [related technology] in that…” Then explain how you’d get up to speed quickly.

What if I blank on a technical question?

Ask for a moment to think—this is normal and professional. If you truly don’t know, say so, but offer related knowledge: “I’m not certain about that specific detail, but I know that…”

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Network engineering interviews in 2026 balance technical fundamentals with modern skills like automation and cloud networking. But the candidates who get offers aren’t always the most technically brilliant—they’re the ones who communicate clearly, demonstrate systematic thinking, and show they can work effectively on a team.

For more career resources, explore our IT certifications guide and cybersecurity careers hub.

Prepare your technical knowledge. Practice explaining concepts simply. Have stories ready that demonstrate how you solve problems. And ask questions that show you’re evaluating them as much as they’re evaluating you.

The networking field isn’t going anywhere. Organizations need people who can keep infrastructure running, adapt to new technologies, and translate complex problems into understandable solutions. If you can demonstrate those abilities in an interview, the offer will follow.