Interview prep
Network engineer interview questions and answers
What do network engineer interviews ask?
They ask how networks really move traffic: subnetting, switching and VLANs, routing, TCP and UDP, the services every host relies on, security and troubleshooting, and they expect you to explain why, not just recite. These 60 questions across eight topics each come with a model answer, the follow-ups to expect, and a lab where you can prove the answer yourself.
Updated
Mock interview
One question at a time. Answer it out loud as you would in the room, then reveal the model answer and rate yourself honestly. Your progress stays in this browser.
Questions by topic
- Subnetting & IP addressing8 questions · 4 entry · 4 midHost counts, block sizes, point-to-point links, VLSM, private ranges, summarization and IPv6 basics.Read the questions
- Switching & VLANs8 questions · 4 entry · 4 midMAC learning, access and trunk ports, native VLAN, inter-VLAN routing, Spanning Tree and EtherChannel.Read the questions
- Routing & OSPF8 questions · 3 entry · 5 midRoute selection, administrative distance, default and static routes, OSPF, EIGRP and VRRP.Read the questions
- TCP, UDP & ports6 questions · 3 entry · 3 midTCP vs UDP, the three-way handshake, well-known ports, sessions, refused vs filtered, and MTU.Read the questions
- DHCP, DNS & ARP8 questions · 5 entry · 3 midDORA, relay, 169.254 addresses, ARP, MAC vs IP, what happens when you open a website, and DNS records.Read the questions
- ACLs, NAT & security8 questions · 5 entry · 3 midStandard vs extended ACLs, the implicit deny, wildcard masks, stateless replies, NAT and PAT, port security and SSH.Read the questions
- Troubleshooting8 questions · 4 entry · 3 mid · 1 seniorA method, ping vs traceroute, ping but no web page, unreachable vs timed out, one-way faults, interface states and err-disabled ports.Read the questions
- Wireless6 questions · 2 entry · 4 midSSID vs BSSID, WPA2-Personal vs Enterprise, 2.4 vs 5 GHz, access point designs and clients with no address.Read the questions
How should you use these questions?
Answer each one out loud before you read the model answer, then prove the answer in the lab it links to.
- Say your answer as you would in the room: the short version first, then the why.
- Compare it with the model answer and the common weak answer under it.
- Prepare for the follow-ups. Interviewers change one detail to see whether your reasoning holds.
- Open the lab and make the network do what you said it would. An answer you have seen work is one you can defend.
Practise on a running network
The lab opens in the browser with no account: build, configure and break a network, then fix it.
Open the labHiring a network engineer?
Run a live interview room: one shared lab with the candidate, helper tools off by default.
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