Top 50 Topic Wise Questions For Network Engineer Basic.
Troubleshooting
1. Q: What steps would you take if a user reports no internet connectivity?
A: Check the physical connection, verify IP settings, test connectivity with ping, check for DHCP issues, and ensure the gateway is reachable.
2. Q: How do you troubleshoot a failed ping test to a specific server?
A: Verify server availability, check DNS resolution, ensure correct routing, and inspect firewalls for blocked ICMP.
3. Q: How do you resolve duplicate IP address conflicts?
A: Identify conflicting devices using arp -a, manually assign unique IPs, and check the DHCP server for misconfigurations.
4. Q: What would you do if a device had an APIPA address (169.x.x.x)?
A: Check the DHCP server's availability and ensure the device can communicate with it.
5. Q: What tools would you use to diagnose packet loss?
A: Tools like ping, traceroute, and network analyzers (Wireshark).
Routing Issues
6. Q: How do you troubleshoot a routing loop?
A: Inspect routing tables, check route advertisements, and use tools like traceroute to identify loops.
7. Q: What steps would you take for an OSPF adjacency issue?
A: Verify matching parameters (area ID, authentication), and MTU settings, and ensure there are no Layer 2 issues.
8. Q: How do you resolve BGP session flapping?
A: Check peer configurations, inspect keepalive/hold timers, and ensure stable network paths.
9. Q: How do you troubleshoot a static route not working?
A: Verify route configuration, ensure the next hop is reachable, and check for overlapping or conflicting routes.
10. Q: What would you check if inter-VLAN routing is not working?
A: Verify VLAN configurations, ensure subinterfaces are configured, and check Layer 3 interfaces' status.
Switching Issues
11. Q: How do you troubleshoot a VLAN mismatch?
A: Check trunk port configurations and ensure both ends have the same VLAN allowed.
12. Q: What would you do if a specific port on a switch is not passing traffic?
A: Check the port status, verify VLAN assignment, inspect cables, and review STP status.
13. Q: How do you troubleshoot STP-related issues?
A: Identify root bridge, check for port states, and verify priority configurations.
14. Q: How do you resolve excessive broadcast traffic?
A: Identify the source of broadcasts using network monitoring tools and segment the network if necessary.
15. Q: What would you check if a MAC address is not appearing in the MAC table?
A: Verify port activity, inspect VLAN settings, and ensure the device is generating traffic.
Wireless Troubleshooting
16. Q: How do you troubleshoot a Wi-Fi network with low signal strength?
A: Check the placement of access points, adjust power levels, and scan for interference.
17. Q: What do you do if a user cannot connect to a Wi-Fi network?
A: Verify SSID, check authentication settings, and inspect wireless logs for errors.
18. Q: How do you resolve frequent Wi-Fi disconnections?
A: Check signal strength, review device roaming settings, and inspect AP logs.
19. Q: What steps would you take if wireless devices experience slow speeds?
A: Analyze channel utilization, adjust channel width, and ensure no bandwidth hogging.
20. Q: How do you identify rogue access points?
A: Use wireless scanning tools like NetSpot or AirMagnet.
Firewall Issues
21. Q: How do you troubleshoot blocked traffic through a firewall?
A: Inspect access control lists (ACLs), check logs for denied traffic, and ensure the correct NAT configuration.
22. Q: What steps would you take if a VPN tunnel is not established?
A: Verify Phase 1/Phase 2 settings, check for pre-shared key mismatches, and ensure both ends are reachable.
23. Q: How do you troubleshoot port forwarding issues?
A: Ensure the correct public IP, port, and internal IP mapping. Check NAT and firewall rules.
24. Q: What do you check if a firewall is not passing traffic?
A: Verify interface statuses, review routing, and check for misconfigured security policies.
25. Q: How do you diagnose high CPU usage on a firewall?
A: Check active sessions, review traffic logs for anomalies, and ensure DDoS protection is enabled.
DNS Troubleshooting
26. Q: What steps do you take if a website is not resolving?
A: Test with nslookup or dig, check DNS server settings, and verify the domain’s DNS records.
27. Q: How do you fix DNS timeout issues?
A: Check the DNS server's health, ensure no network latency, and verify firewall rules.
28. Q: How do you troubleshoot intermittent DNS resolution failures?
A: Review logs, ensure redundancy, and inspect caching configurations.
29. Q: What would you check if internal DNS resolution fails?
A: Verify the DNS zone configuration, inspect replication, and check for stale records.
30. Q: How do you resolve reverse DNS lookup issues?
A: Verify PTR records and ensure they match the forward DNS records.
Performance Issues
31. Q: How do you troubleshoot high latency in a network?
A: Use ping and traceroute to identify bottlenecks, check for congestion, and optimize QoS settings.
32. Q: What would you check if users experience frequent application timeouts?
A: Inspect the application server’s health, review network latency, and analyze logs.
33. Q: How do you troubleshoot slow file transfers over the network?
A: Test bandwidth, check for duplex mismatches, and monitor traffic for bottlenecks.
34. Q: How do you diagnose excessive CPU utilization on a router?
A: Review interface statistics, inspect routing tables, and disable unnecessary services.
35. Q: What steps would you take for network jitter issues?
A: Prioritize traffic with QoS, inspect real-time traffic paths, and reduce congestion.
Security Issues
36. Q: How do you detect a DDoS attack?
A: Monitor traffic patterns, check for excessive connections, and use IDS/IPS.
37. Q: What steps would you take if a network is compromised?
A: Isolate affected systems, analyze logs, and restore from backups.
38. Q: How do you secure an open port discovered during a scan?
A: Disable unused services, apply ACLs, or use a firewall.
39. Q: How do you identify unauthorized access attempts?
A: Analyze syslogs, review failed authentication attempts, and use SIEM tools.
40. Q: What would you do if sensitive data is being leaked?
A: Inspect firewall logs, review outbound traffic, and implement DLP solutions.
General Scenarios
41. Q: How do you troubleshoot a split-horizon issue in routing?
A: Enable route redistribution and check protocol configurations.
42. Q: What do you do if multicast traffic is not being delivered?
A: Verify multicast group membership, inspect IGMP settings, and ensure PIM is configured.
43. Q: How do you resolve MTU mismatches?
A: Use ping with the -f fl ag and adjust MTU settings on affected devices.
44. Q: What steps would you take if QoS is not prioritizing traffic correctly?
A: Verify QoS policies, inspect traffic classification, and ensure queue settings are correct.
45. Q: How do you identify the root cause of network congestion?
A: Use tools like NetFlow, review interface statistics and inspect traffic patterns.
Advanced Troubleshooting
46. Q: How do you troubleshoot MPLS label mismatches?
A: Verify LDP settings, check for duplicate labels, and inspect forwarding tables.
47. Q: What do you check if a VXLAN tunnel is not working?
A: Inspect VTEP settings, verify encapsulation protocols, and ensure multicast is supported.
48. Q: How do you troubleshoot SD-WAN connectivity issues?
A: Check the controller’s reachability, inspect policies, and verify transport links.
49. Q: How do you resolve issues with SNMP monitoring?
A: Verify community strings, check SNMP agent availability, and ensure firewalls allow SNMP traffic.
50. Q: What would you do if a network device firmware upgrade fails?
A: Roll back to the previous firmware, verify compatibility, and reattempt with the correct procedures.
These questions and answers provide a broad foundation for troubleshooting common and advanced network issues.
