100+ Real-World
Scenario-Based
Questions Every
Network Engineer
Must Prepare!
PM Networking
This is a comprehensive list of 100+ scenario-based interview questions
specifically curated for Network Engineers. These questions are designed to
test practical understanding, real-world troubleshooting, configuration, and
decision-making skills from L1 to L3 level across domains like routing, switching,
firewalls, wireless, and network design.
Most network engineers spend hours solving real-world issues, not just
memorizing definitions or commands. Interviewers know this. That’s why
scenario-based questions are becoming the backbone of technical interviews,
L2/L3 assessments, and on-the-job performance reviews.
✅ Routing & Switching
1. You configured OSPF but the routers are not forming neighbor adjacency.
How will you troubleshoot?
2. Two VLANs on the same switch cannot communicate. What could be the
issue?
3. How would you connect two buildings on a campus using switches?
4. A user cannot access the internet but can ping the default gateway. What
will you check next?
5. What would you do if you see flapping routes in the routing table?
6. How do you troubleshoot an asymmetric routing issue?
7. You implemented HSRP but both routers are in active state. Why?
8. Explain what happens if two routers in the same OSPF area have the
same router ID.
9. How would you troubleshoot a scenario where STP is causing frequent
topology changes?
10. A newly added switch is not learning MAC addresses. What do you
check?
⚙️ IP Addressing & Subnetting
11.A user complains of IP conflict. How do you investigate?
12. How do you assign IPs to 500 users efficiently?
13. What would you do if you find overlapping subnets between branches?
14. How would you summarize a group of networks to reduce route entries?
15. How would you allocate a subnet for DMZ hosting public servers?
🧱 Firewall & Security
16. Users can access internal servers but not internet. What could be
wrong on the firewall?
17. Your site-to-site VPN tunnel is up but traffic is not passing. Steps?
18. What would you do if firewall denies internal DNS resolution?
19. You notice huge outbound traffic to a suspicious IP. Steps to analyze?
20. How do you restrict access to a specific website from a corporate
network?
📶 Wireless Networking
21. Users on Wi-Fi complain of frequent disconnections. What will you
check?
22. How do you prevent rogue APs in an enterprise network?
23. How will you implement secure guest Wi-Fi in a hotel?
24. Wi-Fi works on one floor but not on another. How do you begin
troubleshooting?
25. How to deal with channel overlapping in 2.4 GHz?
🛠 Troubleshooting & Monitoring
26. Network is slow intermittently. How will you investigate?
27. A switch CPU is constantly 90%+. What’s your approach?
28. How do you identify and resolve a broadcast storm?
29. User is unable to SSH into a server. What are your first 5 checks?
30. What if a traceroute is failing after the 2nd hop?
🧭 Network Design & Planning
31. How would you design a redundant network for a data center?
32. What factors do you consider when choosing between static and
dynamic routing?
33. How would you scale a network from 10 to 1000 users?
34. How do you design a high-availability solution for a branch office?
35. What is your strategy to segment networks for different departments?
🌐 Internet, NAT, and DNS
36. Explain how you’d configure NAT for multiple internal servers with one
public IP.
37. How would you diagnose DNS resolution failure?
38. What if ping by IP works but not by domain name?
39. How do you implement port forwarding for a web server?
40. Your NAT table is full — what happens and how to resolve?
🔐 Authentication & Access Control
41. How will you implement 802.1X authentication on a switch port?
42. How do you give temporary internet access to a guest device?
43. What is your response to repeated failed login attempts on a network
device?
44. A terminated employee still has access to VPN — what’s your
immediate step?
45. How would you segment traffic using ACLs for Sales and HR
departments?
📡 Cloud & SD-WAN
46. How do you configure site-to-site VPN between HQ and AWS?
47. What happens when one SD-WAN link fails — how is failover handled?
48. How do you troubleshoot packet loss in a cloud-hosted VPN?
49. How do you prioritize VoIP traffic over MPLS and broadband in
SD-WAN?
50. Your cloud-hosted server is inaccessible — how to isolate if it’s a
routing or firewall issue?
📁 Logs, Tools & Documentation
51. What are the key logs you check in a switch/router during failure?
52. Which tools do you use for packet capture and traffic analysis?
53. How do you maintain device inventory and configuration backups?
54. How often should you review firewall rules?
55. What’s your standard procedure for documenting a new network setup?
🧩 Redundancy & Failover
56. How do you verify HSRP failover is working?
57. Your primary ISP link is down — traffic is not failing over. Why?
58. Explain how LACP or EtherChannel helps in redundancy.
59. What’s your strategy for WAN load balancing?
60. How do you monitor active/passive firewall pairs?
🧮 QoS, VoIP & Performance
61. How would you prioritize VoIP traffic over general traffic?
62. What are your steps to troubleshoot choppy voice calls?
63. How do you classify and mark packets for QoS?
64. Your QoS policy is not taking effect — how do you troubleshoot?
65. VoIP packets are getting dropped during peak hours. Next steps?
🧠 Behavioral & Scenario-Based
66. A critical link fails during your shift — what's your escalation process?
67. How do you handle a planned maintenance with minimal disruption?
68. Describe a situation where your quick action prevented major
downtime.
69. A team member made a config error — how would you resolve and
prevent recurrence?
70. You receive conflicting instructions from two managers — how do you
handle it?
🛡️ Network Access & Zero Trust
71. How would you limit access to management ports (SSH/Telnet) of
devices?
72. How do you set up a jump server for managing all routers/switches?
73. What steps do you take to implement role-based access on switches?
74. How would you implement a zero-trust policy in a campus LAN?
75. How do you ensure third-party vendors can only access designated
servers?
🧮 Load Balancing & HA
76. How would you deploy HA for an internal web application?
77. How do you ensure stateful failover between firewall pairs?
78. What’s your approach for designing a load-balanced DNS
infrastructure?
79. How to design application-level redundancy for critical services?
80. Load balancer health checks are failing — what do you check?
🚨 Disaster Recovery & Backup
81. What are your DR strategies for critical routers and switches?
82. How do you backup and restore device configs using TFTP?
83. What’s your network restoration plan in case of major power failure?
84. How do you simulate a failover test in a controlled environment?
85. What’s your RTO/RPO strategy for networking?
📦 Tools & Automation
86. Which network automation tools have you worked with (e.g., Ansible,
Netmiko)?
87. How do you push mass config updates securely?
88. What kind of alerts do you set up in your NMS (e.g., PRTG,
SolarWinds)?
89. Explain how you use SNMP to monitor link status.
90. What’s your response if automation pushes a wrong config?
🧪 Protocols & Layer-wise Issues
91. How do you troubleshoot issues at Layer 2 vs Layer 3?
92. ARP table is incomplete — what’s the impact and solution?
93. BGP route is present but traffic is not flowing — why?
94. How would you troubleshoot MTU mismatch in a link?
95. Explain how you’d troubleshoot a DHCP issue in a VLAN-based setup.
📝 Configuration & Upgrade
96. How do you safely upgrade the firmware of a core switch?
97. What’s your checklist before migrating to a new router?
98. How would you roll back a failed network configuration?
99. What’s your approach to configuring a multi-VRF environment?
100. How do you migrate static routes to dynamic routing in a live network?
🧭 Bonus: Common Interview Traps
101. What’s the difference between port security and 802.1X — when would
you use which?
102. You’re given a task to configure EIGRP over DMVPN — what things will
you consider?
103. Static NAT works, but dynamic NAT doesn’t — how do you proceed?
104. What happens if all interfaces in a switch are in the same VLAN?
105. What’s the risk of using VLAN 1 across the enterprise?
PM Networking
