Network Engineer Interview Questions UK: 8 Real Questions and What Interviewers Want

Before your Network Engineer interview, it helps to see the questions from the interviewer's side. We have picked eight from our set of 25 and added the reason each one gets asked.

Eight Network Engineer interview questions, and what the interviewer is thinking

1. What does a network engineer do day to day, and why do you want to work in networking?

Why they ask: They want to see that you understand both the build and the support sides of the role.

2. Walk me through the OSI model and tell me which layers you troubleshoot most often.

Why they ask: This is almost universal in network interviews, and they want practical application rather than recitation.

3. What is a VLAN, and how do trunking and inter-VLAN routing work?

Why they ask: VLANs are foundational to almost every enterprise network.

4. Explain how OSPF and BGP work and when you would use each.

Why they ask: Routing protocol knowledge is a core expectation for mid-level engineers.

5. What is Spanning Tree Protocol, and what problems does it prevent?

Why they ask: Layer 2 loops can take down a network, so this is a key practical topic.

6. Subnetting: how many usable hosts are in a /26, and how would you split 10.10.0.0/24 into four equal subnets?

Why they ask: Subnetting is practically guaranteed in a network engineer interview.

7. Users at a branch office report that everything is very slow. How would you troubleshoot it?

Why they ask: This is the classic scenario question, and they want a structured methodology.

8. Tell me about a significant network outage you were involved in and how you handled it.

Why they ask: They want to see how you perform under pressure and what you learned.

A sample answer to question 1

What does a network engineer do day to day, and why do you want to work in networking?

My week would blend planned and reactive work. Planned work includes configuring and deploying switches, routers, firewalls and wireless, carrying out upgrades through change control, documenting designs and reviewing capacity. Reactive work means monitoring alerts, troubleshooting outages and performance issues, working with the service desk and carriers, and doing root cause analysis afterwards. I'd also contribute to security hardening, patching firmware and supporting projects such as office moves or SD-WAN rollouts. I'm drawn to networking because everything else depends on it, and I like the combination of logic, design and the satisfaction of finding the fault in a complex system. I enjoy the variety, from reading packet captures to talking with suppliers, and I find it rewarding that a well-designed network is one that nobody notices.

Common mistake to avoid: Describing only fault fixing; Saying you like cables

Want the rest?

Full model answers, key points and common mistakes for all 25 questions are on the Network Engineer interview questions page. The first five are free, no sign-up needed.