Top 100 Interview Questions For IT Support and Answers

Interview Questions For IT Support

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1. What is BIOS?

Answer: BIOS (Basic Input/Output System) is firmware that initializes and manages hardware components when a computer starts.


2. Explain the difference between RAM and ROM.

Answer: RAM (Random Access Memory) is volatile memory used for active data storage, while ROM (Read-Only Memory) is non-volatile and stores firmware.


3. How do you troubleshoot a computer that won’t turn on?

Answer: Check power connections, verify the power outlet, inspect for loose components, and test with a known working power supply.


4. Define IP address.

Answer: An IP address is a unique numerical label assigned to each device on a network, allowing for communication and identification.


5. What is DHCP?

Answer: DHCP (Dynamic Host Configuration Protocol) automatically assigns IP addresses to devices on a network.


6. How do you reset a Windows password?

Answer: Use password reset disks, the command prompt, or administrator accounts to reset a Windows password.


7. What is the purpose of an operating system?

Answer: An operating system manages hardware resources, provides user interfaces, and executes software applications.


8. Explain the concept of a firewall.

Answer: A firewall is a security device that filters network traffic, allowing or blocking data based on predefined rules.


9. How can you troubleshoot a slow computer?

Answer: Check for malware, remove unnecessary startup programs, upgrade hardware, and optimize software.


10. What is RAID?

Answer: RAID (Redundant Array of Independent Disks) is a storage technology that combines multiple drives for data redundancy and improved performance.


11. Define VPN.

Answer: A VPN (Virtual Private Network) securely connects remote users or networks over a public network, such as the internet.


12. Explain the difference between HTTP and HTTPS.

Answer: HTTP (Hypertext Transfer Protocol) is unencrypted, while HTTPS (Hypertext Transfer Protocol Secure) uses SSL/TLS encryption for secure data transfer.


13. What is a DNS server used for?

Answer: DNS (Domain Name System) servers translate human-readable domain names into IP addresses, enabling internet communication.


14. How do you troubleshoot a printer that is not printing?

Answer: Check connections, verify paper and ink/toner, restart the print spooler, and reinstall printer drivers.


15. Explain the purpose of a subnet mask.

Answer: A subnet mask defines network and host portions of an IP address, facilitating routing and addressing.


16. What is a MAC address?

Answer: A MAC (Media Access Control) address is a unique hardware identifier assigned to network devices.


17. How can you recover data from a corrupted hard drive?

Answer: Use data recovery software, consult professionals, or attempt disk repair tools.


18. Define malware.

Answer: Malware is malicious software designed to harm, steal data, or disrupt computer systems.


19. What is a phishing attack?

Answer: Phishing is a cyberattack where malicious actors impersonate trusted entities to trick users into revealing sensitive information.


20. How do you handle a computer virus infection?

Answer: Isolate the infected system, run antivirus software, remove malware, and update security measures.


21. Explain the concept of cloud computing.

Answer: Cloud computing involves accessing and using computing resources (e.g., servers, storage) over the internet, offering scalability and flexibility.


22. How do you secure a wireless network?

Answer: Enable WPA/WPA2 encryption, use strong passwords, change default settings, and update router firmware.


23. What is the purpose of a UPS (Uninterruptible Power Supply)?

Answer: A UPS provides backup power during electrical outages, preventing data loss and protecting hardware.


24. Define IPsec.

Answer: IPsec (Internet Protocol Security) is a suite of protocols for securing internet communication through encryption and authentication.


25. How can you troubleshoot network connectivity issues?

Answer: Check cables, restart networking equipment, use ping/traceroute, and review firewall settings.


26. What is RAID 0?

Answer: RAID 0, also known as striping, combines multiple drives for increased performance but does not provide data redundancy.


27. Explain the purpose of a proxy server.

Answer: A proxy server acts as an intermediary between clients and servers, enhancing security, privacy, and performance.


28. What is a patch management system?

Answer: A patch management system ensures that software and operating systems are up-to-date with the latest security patches and updates.


29. What is the difference between a hub and a switch?

Answer: A hub broadcasts data to all devices in a network, while a switch intelligently forwards data only to the intended recipient, reducing network congestion.


30. How do you troubleshoot a no-boot situation in a PC?

Answer: Inspect hardware connections, check for a malfunctioning power supply, test RAM and motherboard, and evaluate error codes.


31. Explain the concept of a virtual machine.

Answer: A virtual machine (VM) is a software-based emulation of a physical computer, allowing multiple operating systems to run on a single physical machine.


32. What is the purpose of a traceroute command?

Answer: Traceroute is used to trace the path and measure the time it takes for data packets to travel from a source to a destination on a network.


33. Define a backup strategy.

Answer: A backup strategy outlines how data is regularly and securely copied to prevent data loss in case of hardware failure or other disasters.


34. How can you reset network settings in Windows?

Answer: Use the “netsh” command to reset network settings to default in Windows.


35. What is RAID 1?

Answer: RAID 1, also known as mirroring, duplicates data across two drives for data redundancy. If one drive fails, data remains on the other.


36. Explain the purpose of a static IP address.

Answer: A static IP address is manually configured and remains fixed, which is important for servers and network devices that need a consistent address.


37. How can you prevent data loss due to power outages?

Answer: Use UPS devices, surge protectors, and backup power generators to safeguard against data loss during power interruptions.


38. What is the purpose of a BIOS update?

Answer: A BIOS update improves system stability, compatibility, and security by applying firmware enhancements.


39. How can you identify and remove malware from a computer?

Answer: Use reputable antivirus software, scan the system, quarantine or delete threats, and keep the antivirus updated.


40. Define SSL/TLS.

Answer: SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) are cryptographic protocols that secure data transmission over networks like the internet.


41. How can you recover a forgotten password on a Linux system?

Answer: Access the GRUB menu, enter single-user mode, and reset the password using the “passwd” command.


42. What is a proxy server used for in cybersecurity?

Answer: Proxy servers can enhance security by filtering and monitoring web traffic, blocking malicious sites, and protecting user identities.


43. Explain the concept of NAT.

Answer: NAT (Network Address Translation) allows multiple devices on a private network to share a single public IP address for internet access.


44. How can you optimize a computer’s performance?

Answer: Remove unnecessary startup programs, defragment the hard drive, upgrade hardware components, and keep the system updated.


45. What is the purpose of a DMZ (Demilitarized Zone) in network security?

Answer: A DMZ is a network segment that isolates public-facing servers from the internal network, adding an extra layer of security.


46. Define SQL injection.

Answer: SQL injection is a cyberattack that exploits vulnerabilities in web applications to manipulate databases by injecting malicious SQL queries.


47. How do you resolve a “No Internet Access” issue in Windows?

Answer: Troubleshoot network connections, reset the TCP/IP stack, and update network drivers to resolve this issue.


48. What is a DDoS attack?

Answer: A Distributed Denial of Service (DDoS) attack overwhelms a server or network with a flood of traffic, rendering it unavailable to users.


49. Explain the purpose of a subnet.

Answer: A subnet divides a larger network into smaller, more manageable segments to improve security, organization, and performance.


50. How can you secure remote desktop access to a computer?

Answer: Use strong passwords, enable Network Level Authentication (NLA), and limit access to trusted users to secure remote desktop connections.


51. Explain the purpose of a firewall in network security.

Answer: A firewall is a security device or software that filters network traffic, allowing or blocking data based on predetermined security rules, protecting a network from unauthorized access and threats.


52. What is the difference between a full backup and an incremental backup?

Answer: A full backup copies all data in a system, while an incremental backup copies only data that has changed since the last backup, saving storage space and time.


53. Define RAID 5.

Answer: RAID 5 stripes data across multiple drives with distributed parity. It offers data redundancy and improved read performance but requires at least three drives.


54. How do you troubleshoot a printer that’s not responding?

Answer: Check physical connections, printer status, and drivers. Restart the print spooler, update drivers, and ensure the printer is set as the default.


55. Explain the purpose of a VPN (Virtual Private Network).

Answer: A VPN creates a secure, encrypted tunnel over the internet, allowing users to access a private network securely, ideal for remote work or safeguarding sensitive data during transmission.


56. What is a BIOS password, and how can it be reset?

Answer: A BIOS password restricts access to the computer’s BIOS settings. To reset it, you may need to clear CMOS memory by temporarily removing the CMOS battery.


57. How do you troubleshoot a slow internet connection?

Answer: Test the connection speed, check for background downloads or streaming, reboot the router, update firmware, and contact the ISP if needed.


58. Define RAID 0.

Answer: RAID 0, also known as striping, spreads data across multiple drives to improve performance. However, it offers no redundancy, so data loss can occur if one drive fails.


59. What is a MAC address, and how is it used in networking?

Answer: A MAC (Media Access Control) address is a unique identifier assigned to network devices. It’s used to ensure data packets reach the correct destination on a local network.


60. How can you recover a forgotten password on a Windows system?

Answer: Use password reset tools, try “password hint” or security questions, or use another administrator account to reset the password.


61. Explain the purpose of a UPS (Uninterruptible Power Supply).

Answer: A UPS provides backup power during electrical outages, allowing devices to shut down safely, preventing data loss, and protecting hardware.


62. What is the purpose of a DHCP server?

Answer: A DHCP (Dynamic Host Configuration Protocol) server assigns IP addresses automatically to devices in a network, simplifying network management.


63. How can you identify and remove a virus from a computer?

Answer: Use antivirus software to scan for and remove viruses. Quarantine or delete infected files and keep the antivirus updated.


64. Define NAT traversal.

Answer: NAT traversal techniques allow devices behind a NAT firewall to establish connections with devices outside the network, enabling services like VoIP and online gaming.


65. How do you troubleshoot a “Blue Screen of Death” (BSOD) error in Windows?

Answer: Analyze the error message, check for hardware and driver issues, and use system restore or repair tools to resolve the problem.


66. Explain the purpose of a proxy server.

Answer: A proxy server acts as an intermediary between users and the internet, improving security and performance by caching content and filtering web traffic.


67. What is a subnet mask, and how does it work?

Answer: A subnet mask defines the network portion of an IP address. It helps devices determine if a destination IP is on the same local network or needs routing.


68. How can you secure a wireless network?

Answer: Use strong encryption (e.g., WPA3), change default passwords, hide the SSID, enable MAC filtering, and regularly update router firmware.


69. Explain the purpose of a UPSERT operation in databases.

Answer: UPSERT combines “update” and “insert” actions. It either updates an existing record or inserts a new one if it doesn’t exist, based on a unique identifier.


70. What is the purpose of a content delivery network (CDN)?

Answer: A CDN enhances website performance by distributing content across multiple servers geographically, reducing server load and improving user experience.


71. What is a DNS server, and how does it work?

Answer: A DNS (Domain Name System) server translates human-readable domain names into IP addresses. It works by querying a hierarchical system of DNS servers to resolve domain names to their corresponding IP addresses.


72. Explain the purpose of a traceroute command.

Answer: Traceroute is used to trace the route that packets take to reach a destination host on a network. It helps diagnose network problems by showing the hops between routers and the time taken for each.


73. What is a VLAN (Virtual LAN), and why is it used?

Answer: A VLAN is a logical grouping of network devices within a physical network. It’s used to segment and isolate traffic, enhancing network security, and reducing broadcast traffic.


74. How can you troubleshoot an email client that can’t send or receive emails?

Answer: Check email server settings, test internet connectivity, disable antivirus or firewall blocking, and verify email account credentials and server status.


75. Explain what a VPN tunnel is and its significance in network security.

Answer: A VPN tunnel is a secure, encrypted connection between two devices or networks over an untrusted network (usually the internet). It ensures data confidentiality and integrity, making it crucial for secure communications.


76. What is a BIOS update, and why might you need to perform one?

Answer: A BIOS update is a firmware update for a computer’s motherboard. It’s necessary to fix bugs, add compatibility for new hardware, and enhance system stability and security.


77. Describe the purpose of the “ping” command in networking.

Answer: The “ping” command sends ICMP (Internet Control Message Protocol) packets to a target IP address to check if it’s reachable and measure round-trip time. It’s used for network diagnostics and testing connectivity.


78. What is a hardware firewall, and how does it differ from a software firewall?

Answer: A hardware firewall is a physical device placed between a network and external connections, offering robust security. In contrast, a software firewall is installed on individual devices, providing protection at the OS level.


79. Explain RAID 1.

Answer: RAID 1 mirrors data across two drives, ensuring redundancy and fault tolerance. If one drive fails, data remains accessible on the other.


80. How do you troubleshoot a non-responsive keyboard or mouse?

Answer: Check physical connections, replace batteries, test on another computer, and update or reinstall drivers if necessary.


81. Define a “man-in-the-middle” attack and how it can be prevented.

Answer: A man-in-the-middle attack intercepts communication between two parties, often to eavesdrop or tamper with data. Prevention measures include using encryption, strong authentication, and secure channels.


82. What is a patch management system, and why is it essential in IT security?

Answer: A patch management system is used to identify, deploy, and track software patches and updates. It’s crucial for fixing vulnerabilities and ensuring systems are protected against known threats.


83. Explain the purpose of a network switch.

Answer: A network switch connects devices within a local area network, forwarding data to the appropriate destination based on MAC addresses. It improves network efficiency compared to hubs.


84. How can you recover a deleted file on a Windows system?

Answer: Use the “Recycle Bin” for recent deletions or a file recovery tool if the file is permanently deleted. Stop using the drive to prevent overwriting data.


85. Define NAT (Network Address Translation) and its role in networking.

Answer: NAT is a technique that maps private IP addresses to a public IP address. It allows multiple devices on a private network to share a single public IP, improving security and conserving public IP addresses.


86. What is a BIOS password, and how can it be reset?

Answer: A BIOS password restricts access to the computer’s BIOS settings. To reset it, you may need to clear CMOS memory by temporarily removing the CMOS battery.


87. How do you troubleshoot a slow internet connection?

Answer: Test the connection speed, check for background downloads or streaming, reboot the router, update firmware, and contact the ISP if needed.


88. Define RAID 0.

Answer: RAID 0, also known as striping, spreads data across multiple drives to improve performance. However, it offers no redundancy, so data loss can occur if one drive fails.


89. What is a MAC address, and how is it used in networking?

Answer: A MAC (Media Access Control) address is a unique identifier assigned to network devices. It’s used to ensure data packets reach the correct destination on a local network.


90. How can you recover a forgotten password on a Windows system?

Answer:

Use password reset tools, try “password hint” or security questions, or use another administrator account to reset the password.


91. Explain the purpose of a UPS (Uninterruptible Power Supply).

Answer: A UPS provides backup power during electrical outages, allowing devices to shut down safely, preventing data loss, and protecting hardware.


92. What is the purpose of a DHCP server?

Answer: A DHCP (Dynamic Host Configuration Protocol) server assigns IP addresses automatically to devices in a network, simplifying network management.


93. How can you identify and remove a virus from a computer?

Answer: Use antivirus software to scan for and remove viruses. Quarantine or delete infected files and keep the antivirus updated.


94. Define NAT traversal.

Answer: NAT traversal techniques allow devices behind a NAT firewall to establish connections with devices outside the network, enabling services like VoIP and online gaming.


95. How do you troubleshoot a “Blue Screen of Death” (BSOD) error in Windows?

Answer: Analyze the error message, check for hardware and driver issues, and use system restore or repair tools to resolve the problem.


96. Explain the purpose of a proxy server.

Answer: A proxy server acts as an intermediary between users and the internet, improving security and performance by caching content and filtering web traffic.


97. What is a subnet mask, and how does it work?

Answer: A subnet mask defines the network portion of an IP address. It helps devices determine if a destination IP is on the same local network or needs routing.


98. How can you secure a wireless network?

Answer: Use strong encryption (e.g., WPA3), change default passwords, hide the SSID, enable MAC filtering, and regularly update router firmware.


99. Explain the purpose of a UPSERT operation in databases.

Answer: UPSERT combines “update” and “insert” actions. It either updates an existing record or inserts a new one if it doesn’t exist, based on a unique identifier.


100. What is the purpose of a content delivery network (CDN)?

Answer: A CDN enhances website performance by distributing content across multiple servers geographically, reducing server load and improving user experience.