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Technical Interview Preparation-Notes (Module-2)

Learning Hub Last Updated: Oct 21, 2026

LAN/WAN Network Troubleshooting   

         
Section 1: LAN Troubleshooting

Q1. A user reports that the LAN connection is not working. What will you check first?

Answer:

“First, I will check the physical LAN cable and confirm that it is properly connected. Then I will check the link light on the network port, verify that the Ethernet adapter is enabled, and check the IP configuration. Finally, I will test connectivity to the default gateway.”

Steps:

  1. Check the LAN cable.
  2. Check the link light.
  3. Verify the network adapter.
  4. Run ipconfig.
  5. Ping the default gateway.
  6. Test connectivity and document the result.

Q2. The LAN cable is connected, but Windows shows “Network Cable Unplugged.” What will you do?

Answer:

“I will reconnect the cable at both ends and check the Ethernet port light. Then I will test with a known-good cable and another switch port. If the problem continues, I will check the network adapter and escalate if the port or wall connection is faulty.”

Q3. A user has a 169.254.x.x IP address. What does it mean?

Answer:

“This is an APIPA address. It usually means the computer could not obtain an IP address from the DHCP server. I will check the cable or Wi-Fi, network adapter, DHCP availability and switch connection.”

Useful command:

  • ipconfig /all
  • ipconfig /renew

Q4. A user cannot ping the default gateway. How will you troubleshoot?

Answer:

“I will check the physical connection first. Then I will verify the IP address and subnet mask to ensure they are correct. I will check the cable, switch port and VLAN configuration if necessary. I will also remember that some devices block ping, so I will use other connectivity tests if required.”

Q5. LAN works on one computer but not on another at the same desk. What could be the problem?

Answer:

“I will compare the two computers. Since one computer works, the wall connection or switch may be working. I will focus on the affected computer's adapter, cable, IP configuration, driver and network access permissions.”

Q6. A user has network connectivity, but cannot access a shared folder. What will you check?

Answer:

“First, I will check whether the file server is reachable. Then I will verify the user's permissions, security group membership and mapped network drive. If the user receives an access-denied message, I will check share and NTFS permissions.”

Q7. What will you do if a LAN connection keeps disconnecting?

Answer:

“I will check the cable, wall jack and switch port. Then I will review the network adapter driver and power-management settings. I will also check whether the issue affects other users on the same switch.”

Q8. A user receives an IP address but cannot access internal network resources. What will you check?

Answer:

“I will verify the IP address, subnet mask, gateway and DNS settings. Then I will test connectivity to the gateway and the required server. If the network settings appear correct, I will investigate VLAN assignment, firewall rules and access permissions.”

Q9. What is a VLAN, and how can an incorrect VLAN affect an end user?

Answer:

“A VLAN is a logical separation of devices within a network. If a switch port is assigned to the wrong VLAN, the user may receive the wrong IP address or be unable to access the required servers and applications. I would verify the user's network assignment and request a switch-port correction from the network team if needed.”

Q10. Multiple users on the same floor lose LAN connectivity. What will you do?

Answer:

“I will treat this as a possible common infrastructure issue. I will identify the affected users and check whether they share a switch, floor connection or network segment. I will notify the network team and provide the affected locations, time of failure and troubleshooting results.”

Section 2: IP Address, DHCP, DNS and Connectivity

 

Q11. What is the difference between an IP address, subnet mask and default gateway?

Answer:

“An IP address identifies a device on the network. A subnet mask identifies the network portion of the address. A default gateway allows the device to communicate with other networks.”

Example:

  • IP Address:      192.168.1.25
  • Subnet Mask:     255.255.255.0
  • Default Gateway: 192.168.1.1
  • DNS Server:      192.168.1.10

Q12. What is DHCP, and how do you troubleshoot a DHCP issue?

Answer:

“DHCP automatically assigns IP configuration to computers. If a user cannot obtain an IP address, I will check the network connection, adapter, DHCP server availability and IP lease. If multiple users are affected, I will inform the network team.”

Commands:

  • ipconfig /all
  • ipconfig /release
  • ipconfig /renew

Q13. A user can ping an IP address but cannot open a website by name. What is the likely issue?

Answer:

“This suggests a possible DNS issue. I will check the configured DNS server and test name resolution using nslookup. If necessary, I will flush the local DNS cache.”

nslookup example.com

ipconfig /flushdns

Q14. What is the difference between DNS and DHCP?

Answer:

“DHCP automatically assigns network settings to a device. DNS translates domain names into IP addresses. DHCP helps the computer join the network, while DNS helps it find services by name.”

Q15. A user can ping the gateway but cannot access the internet. What will you check next?

Answer:

“I will test connectivity to an external IP address and then test DNS resolution. If the external IP is reachable but domain names fail, I will investigate DNS. If external connectivity also fails, I will check the router, firewall, or WAN connection with the network team.”

Troubleshooting flow:

Gateway → External IP → DNS → Application

Q16. What is the difference between ping and tracert?

Answer:

“Ping checks whether a destination responds over the network. Tracert shows the network hops toward the destination and can help identify where the route may be failing.”

ping 192.168.1.1

tracert example.com

Important: A failed ping or tracert hop does not always prove a fault, because some devices block or deprioritize these probes.

Q17. What is the purpose of nslookup?

Answer:

“nslookup is used to query DNS and check whether a domain name resolves to an IP address. I use it when a user can connect to the network but cannot access a service by its hostname.”

nslookup intranet.company.com

Q18. What will you do if two computers have the same IP address?

Answer:

“I will check for an IP address conflict notification and verify the IP configuration of both computers. I will determine whether the address is assigned by DHCP or configured manually. Then I will correct the duplicate assignment according to company procedures.”

Q19. A user can access a server by IP address but not by hostname. What will you check?

Answer:

“I will investigate name resolution. I will use nslookup to check DNS records, verify the configured DNS server and confirm that the correct hostname is being used. If it is a domain server, I will also check the relevant internal DNS records.”

Q20. What does “Destination host unreachable” mean?

Answer:

“It means that a device reporting the error cannot reach the destination through the current network path. I will check the IP address, subnet, gateway and routing. I will also identify which device generated the message, because that helps locate the problem.”

Section 3: WAN Troubleshooting

 

Q21. What is WAN, and how is it different from LAN?

Answer:

“LAN stands for Local Area Network and connects devices within a local site, such as an office. WAN stands for Wide Area Network and connects different sites or networks over larger distances.”

Example:

  • LAN: Computers connected within an office.
  • WAN: Head office connected to a branch office.

Q22. The head office can access a branch office, but the branch cannot access the head office. What will you check?

Answer:

“I will identify which applications and network paths are affected. Then I will check the branch's LAN connectivity, default gateway, WAN link status and VPN or routing status. I will provide the network team with the source, destination and test results.”

Q23. A branch office suddenly loses connectivity to head office. What will you do?

Answer:

“First, I will confirm whether the branch has local LAN and internet connectivity. Then I will check whether the issue affects all branch users or only one user. I will collect the WAN or VPN status and escalate to the network team or service provider.”

Steps:

  1. Confirm the number of affected users.
  2. Test local LAN.
  3. Test local internet.
  4. Check VPN/WAN status where accessible.
  5. Report the impact and time of failure.
  6. Track restoration.

Q24. The internet works at the branch, but the company applications hosted at head office are unavailable. What could be the issue?

Answer:

“The local internet may be working while the private connection to head office is failing. I will check VPN connectivity, routing, DNS and access to the application server. If other branch users are also affected, I will escalate it as a possible WAN or site-to-site VPN issue.”

Q25. What is a VPN, and how do you troubleshoot a VPN connection problem?

Answer:

“A VPN creates an encrypted connection over a network. If a user cannot connect, I will check internet connectivity, credentials, MFA, VPN client status and the error message. I will also check whether the VPN service is available.”

Steps:

  1. Test internet access.
  2. Verify user authentication and MFA.
  3. Check VPN client and error message.
  4. Check date/time and client updates if relevant.
  5. Check VPN service or gateway status.
  6. Escalate with logs and error details.

Q26. A user connects to VPN successfully but cannot access internal servers. What will you check?

Answer:

“I will confirm that the VPN is connected and check the assigned VPN IP address and routes. Then I will test internal DNS and connectivity to the required server. I will also check whether access policies or split-tunnel settings are affecting the connection.”

Q27. What is packet loss, and how can it affect end users?

Answer:

“Packet loss occurs when network packets fail to reach their destination. It can cause voice-call dropouts, video freezing, slow applications and unstable remote sessions. I will run connectivity tests to identify the affected path and compare results over time.”

Example:

ping -n 50 192.168.1.1

“I will check for packet loss at the gateway and, where appropriate, at external destinations. I will not assume that one failed ping proves packet loss on the network.”

Q28. Users report high latency while accessing a remote application. What will you do?

Answer:

“I will check whether the delay occurs for one user, one branch or all locations. Then I will compare response times to the gateway, remote server and application. I will also check packet loss and WAN utilization with the network team.”

Q29. What is the difference between latency and bandwidth?

Answer:

“Bandwidth is the amount of data a connection can carry per second. Latency is the time it takes data to travel between endpoints. High bandwidth does not necessarily mean low latency.”

Example:

  • Low bandwidth: Large files take longer to transfer.
  • High latency: Remote desktop or interactive applications feel delayed.

Q30. A branch office has very slow internet, but the head office is working normally. What will you investigate?

Answer:

“I will focus on the branch's local network and WAN connection. I will check whether the issue affects wired and wireless users, review bandwidth usage and test latency and packet loss. If required, I will request the network team to check the branch circuit and ISP performance.”

Section 4: Wi-Fi and Network Performance

 

Q31. A user connects to Wi-Fi but receives “No Internet.” What will you do?

Answer:

“I will check whether the laptop has a valid IP address, subnet mask, gateway and DNS server. Then I will ping the gateway, test external connectivity and check DNS. I will also compare with another device on the same Wi-Fi.”

Q32. Wi-Fi disconnects frequently. How will you troubleshoot?

Answer:

“I will determine whether the problem affects one device or multiple users. I will check signal strength, interference, the wireless adapter driver and power-management settings. If several users are affected, I will check the access point with the network team.”

Q33. Wi-Fi works near the access point but not in the meeting room. What could be the reason?

Answer:

“The likely causes are weak signal strength, interference or insufficient access-point coverage. I will test the signal in different locations and compare the results. If coverage is poor, I will report it to the wireless network team.”

Q34. What is an access point (AP)?

Answer:

“A wireless access point allows Wi-Fi devices to connect to a network. If users cannot connect in a particular area, I will check the access point's status, coverage, power and network connection.”

Q35. What is the difference between 2.4 GHz and 5 GHz Wi-Fi?

Answer:

“The 2.4 GHz band generally offers better range but may experience more interference. The 5 GHz band usually offers higher speeds over shorter distances, depending on the environment and equipment.”

“I will check the user's location, signal strength and supported wireless bands before recommending a change.”

Q36. One user has slow Wi-Fi, but other users are working fine. What will you check?

Answer:

“I will focus on the affected laptop. I will check signal strength, adapter driver, background downloads, IP configuration and whether the laptop is connected to the correct network. I will test another location and compare with a working device.”

Q37. What is the difference between a switch, router and modem?

Answer:

“A switch connects devices within a local network. A router forwards traffic between different networks. A modem or other ISP termination device provides the connection to the service provider, depending on the network technology.”

Easy way to remember:

  • Switch: Connects local devices.
  • Router: Connects different networks.
  • Modem/ONT: Terminates the ISP access connection, depending on the service.

Section 5: Practical Network Commands

 

Q38. Which commands do you use for basic network troubleshooting?

Answer:

“I commonly use ipconfig, ping, tracert, nslookup and arp. Each command helps me check a different part of network connectivity.”

CommandPurpose
ipconfig /allView IP and adapter details
pingTest IP connectivity
tracertExamine the route to a destination
nslookupTest DNS resolution
arp -aView the local ARP cache
ipconfig /flushdnsClear the DNS resolver cache
ipconfig /renewRequest a DHCP lease renewal

Q39. What will you do if ipconfig /renew fails?

Answer:

“I will check the exact error message and confirm the adapter is connected and enabled. Then I will check whether the computer is using DHCP, test the physical connection and investigate DHCP availability. If multiple computers are affected, I will escalate to the network team.”

Q40. How do you check whether a network port is reachable?

Answer:

“If I know the server and required TCP port, I can use PowerShell's Test-NetConnection command. This helps determine whether the specific TCP connection can be established.”

Example:

Test-NetConnection server.company.com -Port 443

“If the test fails, I will investigate the server, firewall, routing or service status. I will not assume that the entire network is down.”

Q41. What is the difference between a ping test and a port connectivity test?

Answer:

“Ping tests IP reachability using ICMP. A port connectivity test checks whether a particular TCP port can be reached. A server may block ping while allowing application traffic, so both tests provide different information.”

Q42. What does “Request timed out” mean in a ping test?

Answer:

“It means no ping response was received within the allowed time. The destination may be unreachable, there may be packet loss, or a firewall may be blocking ICMP. I will perform additional tests before deciding where the problem is.”

Q43. How do you check whether the network adapter is working?

Answer:

“I will open Device Manager and check the Network Adapters section. I will look for disabled devices, warning symbols or missing drivers. Then I will verify the adapter status and test the connection.”

Steps:

  1. Open Device Manager.
  2. Expand Network Adapters.
  3. Check the adapter status.
  4. Update or reinstall the driver if appropriate.
  5. Test LAN or Wi-Fi connectivity.

Section 6: Incident Handling and IT Manager Scenarios

 

Q44. How do you troubleshoot a network issue affecting only one user?

Answer:

“I will check the user's device, cable or Wi-Fi, adapter, IP configuration and connectivity. I will compare the results with a working computer in the same location. This helps me isolate whether the issue is device-specific or network-related.”

Q45. How do you troubleshoot a network issue affecting multiple users?

Answer:

“I will identify the affected users, departments and locations. Then I will check for a common point of failure, such as a switch, access point, VLAN, WAN circuit or shared service. I will raise or update the incident and involve the appropriate infrastructure team.”

Q46. What will you do if the network problem is intermittent and cannot be reproduced immediately?

Answer:

“I will record the time of occurrence, affected users, error messages and network conditions. I will run repeated connectivity tests and check available logs. If necessary, I will coordinate with the network team to monitor the connection over time.”

Q47. A VIP user cannot connect to the corporate network just before an important meeting. What will you do?

Answer:

“I will first acknowledge the urgency and check the user's connectivity. I will troubleshoot the basic LAN or Wi-Fi settings and provide a suitable temporary workaround, such as a working wired connection or approved alternative connection. I will keep the user informed and escalate if the issue requires infrastructure support.”

Q48. How do you handle a WAN outage affecting an entire branch office?

Answer:

“I will confirm that multiple users are affected and check whether the local LAN is still working. Then I will gather the circuit or VPN status, outage start time and business impact. I will escalate to the network team or ISP through the approved process and provide regular updates until service is restored.”

Q49. What information should you provide when escalating a LAN or WAN issue?

Answer:

“I will provide the affected users and locations, start time, business impact, error messages, IP configuration and troubleshooting results. I will also include gateway tests, DNS results and any relevant WAN or VPN status.”

Good escalation checklist:

  • Incident number and priority.
  • Affected user/site.
  • Number of affected users.
  • Start time and symptoms.
  • Relevant IP addresses and destinations.
  • Tests performed and results.
  • Business impact.
  • Temporary workaround, if available.

Q50. Explain your complete LAN/WAN troubleshooting approach to an IT Manager.

Answer:

“My approach is to identify the scope first. I determine whether the issue affects one user, multiple users or an entire site. I then check the physical connection, network adapter, IP configuration and default gateway. After that, I test DNS, application connectivity and, where relevant, the WAN or VPN connection. If the issue is outside my scope, I escalate with complete troubleshooting details, keep the user informed and track the incident until resolution.”

 

Q51. A computer shows “Unidentified Network.” How will you troubleshoot it?

Answer:

“First, I will check the LAN cable and network adapter. Then I will check the IP address, subnet mask and gateway. If the IP configuration is incorrect, I will investigate DHCP or the switch port configuration.”

Steps:

  1. Check cable and adapter.
  2. Run ipconfig /all.
  3. Check IP and gateway.
  4. Renew the IP if using DHCP.
  5. Check VLAN or switch configuration if required.

Q52. The LAN port light is blinking, but there is no connectivity. What will you check?

Answer:

“The blinking light usually indicates link activity, but it does not guarantee correct network access. I will check the IP configuration, gateway, VLAN assignment and network permissions.”

Q53. A user receives an IP address but cannot communicate with colleagues on the same LAN. What will you do?

Answer:

“I will check the subnet mask, IP address and VLAN. Then I will test communication with a known working device. I will also check Windows Firewall and whether the devices are actually on the same logical network.”

Q54. A computer cannot access the network after being moved to another desk. Why?

Answer:

“The new wall port may be disconnected, disabled or assigned to a different VLAN. I will test the cable and port, check the IP address and ask the network team to verify the wall port configuration.”

Q55. A LAN connection works after restarting the computer but fails again later. What will you check?

Answer:

“I will check the network adapter driver, power-management settings, cable, switch port and system logs. I will also check whether the issue occurs after sleep, during high network usage or at a particular time.”

Q56. A user reports intermittent LAN connectivity, but the cable appears fine. What next?

Answer:

“I will test with a known-good cable and switch port. I will check for adapter errors, link drops and switch-port errors with the network team. This will help identify whether the issue is with the endpoint or infrastructure.”

Q57. What will you do if the Ethernet adapter is missing from Windows?

Answer:

“I will check Device Manager for the adapter and any driver errors. I will check BIOS settings if appropriate and reinstall the approved network driver. If the adapter remains undetected, I will investigate hardware failure.”

Q58. How do you troubleshoot a disabled Ethernet adapter?

Answer:

“I will open Network Connections, locate the Ethernet adapter and enable it if permitted. Then I will check its status and test connectivity.”

Q59. The computer shows “Connected,” but internal resources are unavailable. What will you check?

Answer:

“I will check the assigned IP address, gateway, DNS and access permissions. Then I will test the required server and determine whether the problem is related to routing, VLAN, firewall or authentication.”

Q60. How do you identify a faulty wall network port?

Answer:

“I will test the computer using a known-good cable and another working wall port. If the computer works on the second port but not the original, I will report the original port for network testing.”

Section 2: IP Addressing, DHCP and Subnetting

 

Q61. What happens when a computer has an incorrect subnet mask?

Answer:

“The computer may incorrectly identify which devices are on its local network. This can cause connectivity problems with local devices or remote networks. I will compare its subnet mask with the approved network configuration.”

Q62. A computer has an IP address but no default gateway. What will you do?

Answer:

“I will check the DHCP configuration or manual network settings. Without a valid default gateway, the computer may communicate locally but cannot normally reach other networks. I will correct the configuration through the approved process.”

Q63. What is a static IP address?

Answer:

“A static IP address is configured manually or reserved so a device consistently receives the same address. Servers, printers and some network devices may use static addressing or DHCP reservations.”

Q64. What is the difference between static IP and DHCP?

Answer:

“With static IP addressing, network settings are configured manually. With DHCP, the network automatically assigns settings to the device.”

Q65. A printer's IP address keeps changing. How will you resolve this?

Answer:

“I will check whether the printer receives its address from DHCP. I will coordinate with the network team to create a DHCP reservation or assign an approved static IP address to ensure consistent access.”

Q66. What is an IP address conflict?

Answer:

“An IP conflict happens when two devices use the same IP address on a network. It can cause intermittent connectivity. I will identify the conflicting devices and correct the duplicate address assignment.”

Q67. What is APIPA?

Answer:

“APIPA stands for Automatic Private IP Addressing. Windows may assign itself an address in the 169.254.x.x range when it cannot obtain an IPv4 address from DHCP.”

Q68. What is the DHCP DORA process?

Answer:

“DORA describes the four main steps of DHCP address allocation.”

  • Discover: Client searches for a DHCP server.
  • Offer: Server offers an address.
  • Request: Client requests the offered address.
  • Acknowledge: Server confirms the lease.

Q69. How do you troubleshoot a DHCP scope that has run out of IP addresses?

Answer:

“If multiple users cannot obtain IP addresses, I will inform the network team and provide the affected subnet and error details. The team can check available leases, reservations and scope utilization before expanding or correcting the scope.”

Q70. What is a subnet?

Answer:

“A subnet is a smaller logical network within a larger IP network. Subnetting helps organize devices, manage IP addresses and control network traffic.”

Q71. What does /24 mean in an IP address such as 192.168.1.25/24?

Answer:

“The /24 is CIDR notation indicating that 24 bits identify the network portion. Its corresponding IPv4 subnet mask is 255.255.255.0.”

Q72. A user receives an IP address from the wrong subnet. What could be the reason?

Answer:

“Possible causes include an incorrect VLAN, wrong DHCP scope, an incorrect static IP or an unauthorized DHCP server. I will check the device configuration and escalate the VLAN or DHCP investigation to the network team.”

Q73. What is a DHCP reservation?

Answer:

“A DHCP reservation links a device's identifier, usually its MAC address, to a specific IP address on the DHCP server. This allows the device to receive the same address through DHCP.”

Q74. What is the difference between a MAC address and an IP address?

Answer:

“A MAC address identifies a network interface at the data-link layer, while an IP address provides logical addressing for communication across IP networks. Network interfaces use both for different purposes.”

Q75. How do you find a computer's MAC address?

Answer:

“I will open Command Prompt and run ipconfig /all. I will locate the relevant Ethernet or Wi-Fi adapter and read its Physical Address field.”

ipconfig /all

Section 3: DNS and Name Resolution

 

Q76. A user cannot access an internal application using its hostname. What will you check?

Answer:

“I will check whether the hostname resolves using nslookup. Then I will verify the configured DNS server and test connectivity to the resolved IP address.”

Q77. What is the difference between a DNS server and a DHCP server?

Answer:

“A DNS server resolves names to IP addresses. A DHCP server assigns network settings to clients. Both services are important, but they solve different problems.”

Q78. What happens when a DNS server is unavailable?

Answer:

“Name-based access to websites and internal services may fail. Direct access by IP might still work, depending on routing and application configuration. I will check DNS settings and test name resolution.”

Q79. What is a DNS cache?

Answer:

“A DNS cache temporarily stores name-resolution results so the computer does not need to query DNS every time. If the cached information is outdated, flushing the cache may help.”

ipconfig /flushdns

Q80. What is the difference between a DNS A record and a CNAME record?

Answer:

“An A record maps a hostname to an IPv4 address. A CNAME record points one hostname to another hostname.”

Q81. A website opens by IP address but not by domain name. What will you check?

Answer:

“I will investigate DNS resolution, check the DNS server and use nslookup to see whether the domain resolves correctly. I will also consider whether the application depends on a hostname for secure connections or virtual hosting.”

Q82. How do you check which DNS server a computer is using?

Answer:

“I will run ipconfig /all and look for the DNS Servers field under the active network adapter.”

Q83. What is split DNS?

Answer:

“Split DNS means different DNS responses may be provided for the same domain depending on whether the query comes from an internal or external network. It is often used to provide internal access to company services.”

Q84. A user can access an application by IP but gets a certificate error when using its name. What will you do?

Answer:

“I will check the hostname, DNS resolution, certificate validity and system date and time. I will not advise the user to bypass the certificate warning. I will escalate any certificate or server configuration issue.”

Q85. What is a hosts file, and how can it affect connectivity?

Answer:

“The Windows hosts file can manually map hostnames to IP addresses. An incorrect entry may send a user to the wrong address. I will inspect it only when appropriate and follow company security procedures before changing it.”

Section 4: Switching, Routing and VLANs

 

Q86. What is the difference between a switch and a router?

Answer:

“A switch connects devices within a local network. A router forwards traffic between different IP networks, such as between an office LAN and a WAN.”

Q87. What is a managed switch?

Answer:

“A managed switch allows administrators to configure and monitor features such as VLANs, port status, speed, duplex and network statistics.”

Q88. What is a switch port?

Answer:

“A switch port is a physical connection where an endpoint or another network device connects to the switch. Its configuration determines how that connection operates.”

Q89. What is an access port?

Answer:

“An access port typically carries traffic for one assigned VLAN and is commonly used for end-user computers, printers and similar devices.”

Q90. What is a trunk port?

Answer:

“A trunk port carries traffic for multiple VLANs between compatible network devices. It is commonly used between switches or between a switch and another network device.”

Q91. What is a VLAN mismatch?

Answer:

“A VLAN mismatch occurs when a device or switch port is assigned to an incorrect VLAN or the VLAN configuration does not match the intended network design. This can prevent access to required resources.”

Q92. What is inter-VLAN routing?

Answer:

“Inter-VLAN routing allows devices in different VLANs to communicate through a router or Layer 3 switch, subject to routing and security policies.”

Q93. A user can communicate with local devices but not with a different subnet. What will you check?

Answer:

“I will check the default gateway, subnet mask, routing and firewall policies. If the issue affects multiple users, I will investigate the routing between the relevant VLANs with the network team.”

Q94. What is a routing table?

Answer:

“A routing table contains information about network destinations and the next hop or interface used to reach them. Incorrect or missing routes can prevent access to remote networks.”

Q95. How can you view the Windows routing table?

Answer:

“I will use the route print command to view the IPv4 and IPv6 routing tables.”

route print

Q96. What is a default route?

Answer:

“A default route is used when no more specific route matches the destination. On a typical end-user computer, the default route points toward the default gateway.”

Q97. What is a network loop?

Answer:

“A network loop can occur when redundant Layer 2 connections create a circular forwarding path. It can cause broadcast storms and network instability. I would report widespread connectivity problems to the network team for switch and Spanning Tree investigation.”

Q98. What is Spanning Tree Protocol (STP)?

Answer:

“STP helps prevent Layer 2 switching loops by controlling redundant paths. It allows network redundancy while preventing loops from disrupting the network.”

Q99. A switch port shows errors or frequent link flaps. What will you do?

Answer:

“I will check the endpoint cable and network adapter first. I will record the times of disconnection and ask the network team to inspect switch-port counters, speed/duplex settings and physical-layer errors.”

Q100. What is PoE, and how can it affect end users?

Answer:

“PoE stands for Power over Ethernet. It allows compatible devices, such as access points and IP phones, to receive power through the network cable. If PoE power is unavailable or insufficient, the device may not start correctly.”

Section 5: WAN, VPN and Remote Connectivity

 

Q101. What is a WAN circuit?

Answer:

“A WAN circuit is a connection that links geographically separate networks or offices. It may be provided through technologies such as Ethernet services, MPLS, leased lines or internet-based VPNs.”

Q102. What is MPLS?

Answer:

“MPLS stands for Multiprotocol Label Switching. It is used by service providers and enterprises to forward traffic through labelled paths and support managed network services.”

Q103. What is the difference between a site-to-site VPN and a remote-access VPN?

Answer:

“A site-to-site VPN connects networks at different locations. A remote-access VPN connects an individual user's device to a company network.”

Q104. A user cannot connect to the corporate VPN. What will you check?

Answer:

“I will check internet connectivity, VPN credentials, MFA, client status and the error message. If the issue affects multiple users, I will check for a VPN gateway or service outage and escalate.”

Q105. The VPN connects successfully, but internal applications remain unavailable. What will you check?

Answer:

“I will check the assigned VPN IP address, routes, internal DNS and application reachability. I will also check access policies and whether the relevant internal network is included in the VPN configuration.”

Q106. What is split tunneling in a VPN?

Answer:

“Split tunneling allows selected traffic to go through the VPN while other traffic uses the user's normal internet connection. Whether this is enabled depends on company security policy.”

Q107. A branch office loses WAN connectivity, but local printing still works. What does this indicate?

Answer:

“It suggests the local LAN may still be operational while connectivity to remote sites or central services is unavailable. I will test the local gateway and internet connection and escalate the WAN issue.”

Q108. What is a WAN failover link?

Answer:

“A failover link is a backup connection that can take over when the primary WAN or internet circuit fails. I would check whether failover occurred and whether the backup link is providing the expected connectivity.”

Q109. How do you troubleshoot a WAN outage with an ISP?

Answer:

“I will confirm the affected site and outage start time, check local equipment and gateway connectivity, and gather available circuit status and logs. I will raise a provider ticket with the circuit reference and business impact, then track updates until restoration.”

Q110. What is an SLA in network support?

Answer:

“An SLA, or Service Level Agreement, defines agreed service targets such as response and restoration times. During an outage, I will track the incident against the relevant SLA and keep stakeholders updated.”

Section 6: Network Performance and Packet Troubleshooting

 

Q111. Users report slow network performance. What is your approach?

Answer:

“First, I will determine whether the problem affects one user, one department or the entire site. Then I will check connectivity, latency, packet loss, Wi-Fi signal and network utilization. I will use the results to isolate the likely cause.”

Q112. What is packet loss?

Answer:

“Packet loss occurs when packets sent across a network do not reach their destination. It can cause voice-call issues, video freezing, slow applications and remote desktop disconnections.”

Q113. What is latency?

Answer:

“Latency is the time taken for data to travel between two endpoints. High latency can make remote applications and interactive sessions feel slow even when bandwidth is sufficient.”

Q114. What is jitter?

Answer:

“Jitter is the variation in packet arrival times. High jitter can affect real-time applications such as VoIP and video conferencing.”

Q115. What is bandwidth?

Answer:

“Bandwidth is the data-carrying capacity of a connection, usually measured in bits per second. If bandwidth is heavily utilized, users may experience slower transfers and application performance.”

Q116. How do you check packet loss using Windows?

Answer:

“I can send repeated ping requests to a destination and check the percentage of lost packets.”

ping -n 50 192.168.1.1

“I will repeat the test where appropriate and compare the results. A single failed ping does not necessarily prove a network fault.”

Q117. What is the purpose of pathping?

Answer:

“pathping combines route discovery with repeated packet testing to help investigate packet loss along a path.”

pathping example.com

“Intermediate devices may limit responses to diagnostic probes, so I will interpret the results alongside other evidence.”

Q118. What is the difference between tracert and pathping?

Answer:

“tracert helps show the route to a destination. pathping performs additional testing to estimate packet loss and latency characteristics along that route.”

Q119. What causes high network utilization?

Answer:

“Possible causes include large file transfers, cloud backups, software updates, video streaming or too many users sharing limited bandwidth. I will check whether utilization is high on one computer or across the network.”

Q120. A user reports that Teams calls freeze while normal browsing works. What will you check?

Answer:

“I will check Wi-Fi or LAN stability, latency, packet loss, jitter and available bandwidth. I will also check whether other real-time applications are affected and review the device's CPU and memory usage.”

Q121. A network connection is fast for downloads but slow for uploads. What will you check?

Answer:

“I will verify the upload and download results using an approved test. Then I will check the connection type, local network usage, Wi-Fi conditions and any upload limits or security inspection. If the problem affects the site, I will escalate it to the network team or ISP.”

Q122. Why might a network speed test show good results while an application remains slow?

Answer:

“A speed test measures only certain aspects of connectivity. The application may be affected by server performance, DNS, latency, packet loss, authentication or application-specific bottlenecks.”

Q123. What is MTU?

Answer:

“MTU stands for Maximum Transmission Unit. It is the largest packet size that can be carried in a network layer without fragmentation at that layer. An incorrect MTU along a path can cause some connections to fail or behave unexpectedly.”

Q124. A VPN connection works, but some websites or applications fail to load. Could MTU be involved?

Answer:

“Yes, a path MTU or fragmentation problem is one possibility. I will collect the affected destinations and symptoms, compare behavior with and without the VPN if permitted, and escalate the evidence to the network team rather than changing MTU settings without approval.”

Q125. What is duplex mismatch?

Answer:

“A duplex mismatch occurs when connected Ethernet interfaces use incompatible duplex settings. It can cause poor performance and errors. I would check link statistics and ask the network team to verify both ends of the connection.”

Section 7: Firewalls, Ports and Network Security

Q126. What is a firewall?

Answer:

“A firewall controls network traffic based on configured security rules. If an application cannot connect, I will check whether the required traffic is being blocked, using approved troubleshooting tools and logs.”

Q127. A user can access the internet but cannot connect to a particular server port. What will you check?

Answer:

“I will verify the server name, destination IP and required port. Then I will use Test-NetConnection and check whether the server service is running or a firewall is blocking the connection.”

Test-NetConnection server.company.com -Port 443

Q128. What is the difference between a port being closed and a port being blocked?

Answer:

“A closed port generally means the destination is reachable but no service is listening on that port. A blocked port may be filtered by a firewall or another network control. The exact behavior depends on the device and configuration.”

Q129. What is a proxy server?

Answer:

“A proxy server acts as an intermediary for network requests. Companies may use proxies for security, filtering, logging or access control. Incorrect proxy settings can prevent users from accessing websites.”

Q130. A user can browse using one browser but not another. What will you check?

Answer:

“I will compare the browser's proxy settings, extensions, DNS behavior and security configuration. I will also check whether the issue is specific to a profile or application before changing system-wide network settings.”

Q131. What is a MAC address allowlist?

Answer:

“A MAC allowlist permits devices with specified MAC addresses to connect under a particular network policy. If a device is not authorized, I will follow the company process to verify and register it rather than bypassing access controls.”

Q132. What is 802.1X authentication?

Answer:

“802.1X is a network access-control framework used to authenticate devices or users before allowing network access. If authentication fails, I will collect the error details and check the approved supplicant configuration, credentials or certificates.”

Q133. A user can connect to Wi-Fi but cannot access company resources because of authentication. What will you do?

Answer:

“I will check the authentication error, user or device credentials and certificate status. I will confirm whether the user is authorized for the network and escalate to the identity or network team if the issue requires policy changes.”

Q134. Why should end users not bypass firewall or certificate warnings?

Answer:

“These warnings may indicate a security risk, an untrusted connection or a policy restriction. I will follow the approved security process and escalate the issue instead of bypassing the control.”

Q135. How do you troubleshoot a blocked application without disabling the firewall?

Answer:

“I will identify the application, destination and required port. I will test connectivity and check approved logs or security alerts. If a rule change is required, I will submit the evidence to the authorized security or network team.”

Section 8: Remote Access, Printers and Network Services

 

Q136. A network printer is online, but users cannot print. What will you check?

Answer:

“I will check whether the printer responds on the network and whether the issue affects one user or everyone. Then I will check the printer IP, print server, queue, driver and permissions.”

Steps:

  1. Check printer status.
  2. Test connectivity to its IP.
  3. Check print queue.
  4. Check the print server.
  5. Check the driver and permissions.

Q137. A user cannot connect to a shared network drive using its mapped drive letter. What will you do?

Answer:

“I will check whether the file server is reachable and whether the drive mapping is disconnected. Then I will test the UNC path, such as \\fileserver\shared, and verify the user's permissions.”

Q138. How do you troubleshoot a Remote Desktop connection failure?

Answer:

“I will check whether the target computer is reachable, whether Remote Desktop is enabled and whether the user has permission. I will also check firewall rules and TCP port 3389 where applicable.”

Q139. What is the difference between RDP and VPN?

Answer:

“RDP allows a user to remotely control a computer. VPN creates a secure network connection that can provide access to internal resources. A user may need a VPN before connecting through RDP, depending on the company's setup.”

Q140. A user cannot access an internal website while connected remotely. What will you check?

Answer:

“I will check the remote connection, VPN status, DNS resolution, routing and application access permissions. I will also compare the behavior with a user who can access the website successfully.”

Section 9: Network Hardware and Troubleshooting Scenarios

 

Q141. What is the difference between a router and a firewall?

Answer:

“A router forwards traffic between networks using routing information. A firewall enforces security rules to allow or block traffic. Some devices perform both functions.”

Q142. An access point is powered on, but no users can connect. What will you check?

Answer:

“I will check whether the SSID is being broadcast, whether the access point is connected to the network and whether it has power and management connectivity. I will also check authentication and configuration with the wireless team.”

Q143. A switch is powered on, but all connected computers are offline. What could be the reason?

Answer:

“Possible causes include an uplink failure, switch configuration problem, power issue or network loop. I will identify the affected switch and users, check the available status indicators and escalate to the network team.”

Q144. What is a network loop, and what symptoms can it cause?

Answer:

“A Layer 2 network loop can create excessive broadcast traffic and disrupt connectivity. Symptoms may include widespread slowness, packet loss and unstable switch ports. The network team should investigate the switching topology and Spanning Tree status.”

Q145. What is the purpose of an ONT in a fiber internet connection?

Answer:

“An Optical Network Terminal converts the provider's optical fiber connection into an interface that customer equipment can use, commonly Ethernet. If the ONT shows a loss-of-signal alarm, I will record the indicator status and escalate to the ISP.”

Section 10: Real-World IT Manager Scenarios

 

Q146. The network fails every day around the same time. How will you investigate?

Answer:

“I will record the exact time, duration and affected users. I will check whether scheduled backups, large transfers, network congestion, power events or ISP issues occur at that time. I will use logs and monitoring evidence to identify the recurring cause.”

Q147. A user says the network is down, but all basic tests are successful. What will you do?

Answer:

“I will clarify which application or business task is failing. I will check application-specific connectivity, DNS, proxy, authentication and server status. Basic ping success does not prove that every application service is working.”

Q148. You receive five network tickets from different users at the same time. How will you prioritize them?

Answer:

“I will assess the business impact and urgency. If the tickets point to one shared network outage, I will link the reports to a common incident and prioritize the wider impact. I will follow the company's priority and escalation process.”

Q149. The network team says the WAN is working, but users still cannot access the application. What will you do?

Answer:

“I will confirm the exact destination and error message. Then I will test DNS resolution, routing, required application ports and server availability. I will share the test results with the network and application teams so they can identify the next point of failure.”

Q150. An IT Manager asks you to explain how you handled a major network outage. How should you answer?

Answer:

“First, I confirmed the scope and identified the affected users and locations. I checked local connectivity and gathered the relevant IP, gateway and remote connectivity results. I raised the incident with the network team, communicated the impact and kept users updated. After service was restored, I documented the root cause, resolution and any preventive actions.”