Network Engineer Interview Questions

1.1The OSI and TCP/IP models - layers, protocols at each layer, and how data moves across a network

1.2IP addressing - IPv4, IPv6, subnetting, CIDR notation, and address planning

1.3Switching fundamentals - VLANs, spanning tree, MAC addresses, and how switches build their tables

1.4Routing fundamentals - routing tables, static routes, and how routers make forwarding decisions

2.1OSPF - link-state routing, areas, DR/BDR election, and troubleshooting common OSPF issues

2.2BGP - path vector routing, AS numbers, attributes, and the protocol that runs the internet

2.3Route redistribution - connecting different routing domains and managing the complexity it introduces

2.4Dynamic routing fundamentals - how routers share topology information and converge after a change

3.1Enterprise LAN design - access, distribution, and core layers and modern collapsed core designs

3.2Spanning Tree Protocol - STP, RSTP, and preventing loops in a switched network

3.3EtherChannel - link aggregation, LACP, and adding redundancy and bandwidth

3.4Inter-VLAN routing - Layer 3 switches, SVIs, and routing between VLANs efficiently

4.1WAN technologies - MPLS, leased lines, broadband, and the trade-offs between them

4.2SD-WAN - the architecture, benefits, and the migration from traditional WAN to software-defined connectivity

4.3Internet connectivity - dual ISP and resilient internet design

4.4WAN performance - latency, jitter, bandwidth, and managing WAN quality for real-time applications

5.1Firewall architecture - zone-based design, stateful inspection, and enterprise firewall deployment

5.2Access control lists - the logic, syntax, and applying ACLs correctly without breaking connectivity

5.3Network segmentation - DMZ design, micro-segmentation, and limiting the blast radius of a breach

5.4VPN technologies - IPsec, SSL VPN, site-to-site and remote access, and securing remote connectivity

6.1Wireless standards - 802.11 protocols, frequency bands, and understanding the alphabet of Wi-Fi

6.2Wireless design - site surveys, access point placement, channel planning, and capacity planning

6.3Wireless security - WPA2, WPA3, 802.1X, RADIUS, and securing enterprise wireless

6.4Wireless troubleshooting - RF interference, coverage gaps, roaming issues, and fixing wireless complaints

7.1Network automation fundamentals - why networks need to be automated and where to start

7.2Python for network engineers - scripts for configuration, data collection, and change validation

7.3Ansible for networking - playbooks, modules, and automating configuration management

7.4APIs and network programmability - NETCONF, RESTCONF, and modern network management

8.1Network monitoring - SNMP, syslog, NetFlow, and building visibility into the network

8.2Troubleshooting methodology - a structured approach to isolating and resolving network faults

8.3Packet capture and analysis - using capture tools to see what is actually happening on the wire

8.4Performance troubleshooting - diagnosing latency, packet loss, and bandwidth saturation issues

9.1Cloud networking fundamentals - VPCs, subnets, routing, and security groups in cloud environments

9.2Hybrid connectivity - Direct Connect, ExpressRoute, and connecting on-premises to cloud

9.3Software-defined networking - SDN concepts, network virtualisation, and overlay networks

9.4IPv6 deployment - planning, dual-stack operation, and migrating an enterprise network to IPv6

10.1Technical questions - routing protocols, switching, firewall design, and WAN connectivity

10.2Troubleshooting questions - diagnosing a described network fault under interview conditions

10.3Scenario and design questions - designing a network for a given set of requirements

10.4Salary negotiation for network engineering roles, evaluating a network environment, and questions that reveal the real network operations maturity