1. You can ping an IP but not the domain. What do you check?

  2. DNS resolves but HTTPS connection fails. What could be the issue?

  3. Clients receive IP addresses but cannot access the internet. Why?

  4. A website loads slowly during peak hours. What do you investigate?

  5. A TLS handshake fails but TCP connects successfully. What does it mean?

  6. A host can reach external networks but not an internal subnet. Why?

  7. Users cannot access the application after enabling IPv6. What do you check?

  8. How do you detect a routing loop?

  9. One region can access an application while another cannot. How do you troubleshoot?

  10. What is the difference between “Connection refused” and “Connection timed out”?

  11. Two servers in different VLANs cannot communicate. What could be wrong?

  12. Production traffic fails after a firewall rule update. What steps would you take?

  13. A service works internally but not externally. What do you check?

  14. SSH works but HTTP downloads are slow. Why?

  15. There is intermittent packet loss to a remote server. How do you diagnose it?

  16. Users say the internet is slow but only for one application. What do you check?

  17. One host cannot reach the gateway but others can. What could be the issue?

  18. DNS resolves but curl https://domain fails with a timeout. What do you check next?

  19. A container cannot communicate with another container in Docker. How do you debug?

  20. Kubernetes pods cannot reach a service. What checks do you perform?

  21. A server cannot resolve DNS names. What files do you inspect?

  22. How do you debug MTU-related issues?

  23. What tools help detect packet drops in a network?

  24. How do you identify bandwidth bottlenecks?

  25. A website shows an SSL certificate error. What could be wrong?

  26. How do you troubleshoot NAT problems?

  27. What steps do you follow when a network suddenly goes down?

  28. A switch port is up but there is no connectivity. What do you check?

  29. Why might DHCP fail to assign IP addresses?

  30. How do you troubleshoot intermittent connectivity problems?