IT Administrator Interview Questions & Answers

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 IT Administrator Interview Questions & Answers ( 70 Nos. Q & A)

IT Administrator Interview Questions & Answers

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

Answer:

  • A switch connects devices within a local network (LAN) and uses MAC addresses to forward data.

  • A router connects multiple networks (LAN to WAN) and forwards data using IP addresses.

2. How do you assign a static IP address in Windows?

Answer:

  • Go to Control Panel > Network & Sharing Center > Change Adapter Settings

  • Right-click on the network adapter → Properties

  • Select Internet Protocol Version 4 (TCP/IPv4) → Click Properties

  • Choose "Use the following IP address" and enter IP, Subnet Mask, and Default Gateway.

3. How do you join a computer to a domain?

Answer:

  • Right-click This PC > Properties > Change Settings

  • Under Computer Name, click Change

  • Select Domain, enter the domain name (e.g., company.local), and enter domain admin credentials.

4. What is Active Directory?

Answer:
Active Directory (AD) is a Microsoft service used to manage users, computers, and resources in a network. It stores information in a centralized database and provides authentication and access control.

5. What is the difference between a workgroup and a domain?

Answer:

  • Workgroup: Peer-to-peer, no centralized management, ideal for small setups.

  • Domain: Centralized management through Active Directory, ideal for large organizations.

6. What is DHCP and how does it work?

Answer:
DHCP (Dynamic Host Configuration Protocol) automatically assigns IP addresses to devices in a network. The DHCP server provides IP, subnet mask, gateway, and DNS information to the client.

7. What are the common Windows Server roles?

Answer:

  • AD DS (Active Directory Domain Services)

  • DNS Server

  • DHCP Server

  • File and Storage Services

  • Web Server (IIS)

  • Print Services

8. What is DNS and how does it work?

Answer:
DNS (Domain Name System) translates human-readable domain names (e.g., google.com) into IP addresses. It helps users access websites without needing to remember numeric IPs.

9. How do you troubleshoot if a user cannot connect to the internet?

Answer:

  • Check if the network cable/Wi-Fi is connected

  • Use ipconfig and ping commands to test connectivity

  • Check IP address configuration

  • Restart router or switch if necessary

  • Check DNS settings

  • Try resetting the network adapter

10. What is Group Policy in Windows?

Answer:
Group Policy is used to centrally manage and configure operating systems, user settings, and applications in an Active Directory environment.

11. What are some common Windows commands used for troubleshooting?

Answer:

  • ipconfig – View IP configuration

  • ping – Test network connection

  • tracert – Trace route to a destination

  • nslookup – DNS lookup

  • netstat – View active connections

  • gpupdate /force – Refresh group policy

  • sfc /scannow – Check system file integrity

12. What is a BSOD and how do you troubleshoot it?

Answer:
BSOD (Blue Screen of Death) indicates a system crash. Common causes include:

  • Driver issues

  • RAM failure

  • Corrupt system files
    Steps: Check error code, update drivers, run memory tests, and use sfc /scannow.

13. What is RAID and what are its types?

Answer:
RAID (Redundant Array of Independent Disks) is used for data protection and performance.

Common RAID levels:

  • RAID 0 – Striping (speed, no redundancy)

  • RAID 1 – Mirroring (redundancy)

  • RAID 5 – Parity (speed + redundancy)

  • RAID 10 – Combination of RAID 1 + 0 (best of both)

14. How do you reset a forgotten Windows Admin password?

Answer:

  • Use a bootable recovery disk

  • Use command prompt in recovery mode:
    Replace utilman.exe with cmd.exe and reset the password with:
    net user administrator newpassword

15. What’s the difference between public and private IP addresses?

Answer:

  • Private IP: Used inside local networks (e.g., 192.168.x.x)

  • Public IP: Used on the internet, assigned by ISP

16. What is a firewall and why is it important?

Answer:
A firewall is a security system that monitors and controls incoming and outgoing network traffic. It protects systems from unauthorized access and cyber threats.

17. What antivirus solutions are commonly used in companies?

Answer:

  • Quick Heal

  • Kaspersky Endpoint

  • Windows Defender (built-in)

  • Symantec

  • Sophos

  • McAfee

18. How do you take a remote desktop connection?

Answer:

  • Enable RDP: System > Remote Settings > Allow Remote Connections

  • Use Remote Desktop Connection (mstsc) tool

  • Enter IP or hostname → login with credentials

19. What is the difference between SSD and HDD?

Answer:

  • SSD (Solid State Drive): Faster, no moving parts, more expensive

  • HDD (Hard Disk Drive): Slower, mechanical parts, cheaper

20. How do you backup and restore data in Windows?

Answer:
Use Windows Backup or tools like Acronis, Macrium Reflect, or built-in File History.
Steps:

  • Choose backup location

  • Select folders/files

  • Set schedule

  • To restore: Use backup tool’s restore feature or copy files manually.

21. What is the default port for RDP?

Answer: Port 3389.

22. What is the difference between IPv4 and IPv6?

Answer:

  • IPv4: 32-bit, e.g., 192.168.1.1

  • IPv6: 128-bit, e.g., 2001:0db8:85a3::8a2e:0370:7334
    IPv6 allows more addresses than IPv4.

23. What is the use of Safe Mode in Windows?

Answer:
Safe Mode starts Windows with minimal drivers and services for troubleshooting system issues.

24. How to check if a port is open on a server?

Answer:
Use command:

bash
telnet <IP> <port>

or

powershell
Test-NetConnection -ComputerName <host> -Port <port>

25. What is a VLAN?

Answer:
A VLAN (Virtual LAN) logically segments a network, improving security and traffic management.

26. What is the use of the Hosts file?

Answer:
It maps hostnames to IP addresses manually before DNS resolution. Located at:
C:\Windows\System32\drivers\etc\hosts

27. How do you flush the DNS cache in Windows?

Answer:
Run ipconfig /flushdns in Command Prompt.

28. What is the role of a DNS forwarder?

Answer:
It forwards DNS queries from a DNS server to external DNS servers for resolution.

29. What is a domain controller?

Answer:
A server that responds to authentication requests and verifies users in a domain.

30. What’s the difference between NTFS and FAT32?

Answer:

  • NTFS: Supports permissions, encryption, large files.

  • FAT32: No permissions, supports max 4GB files.

31. What are FSMO roles in Active Directory?

Answer:

  • Schema Master

  • Domain Naming Master

  • RID Master

  • PDC Emulator

  • Infrastructure Master

32. How to create a user using CMD?

Answer:

cmd
net user username password /add

33. How to map a network drive using command line?

Answer:

cmd
net use Z: \\servername\sharename

34. What is BitLocker?

Answer:
BitLocker is a Windows encryption feature to protect data on drives.

35. How to check disk health?

Answer:
Use chkdsk or tools like CrystalDiskInfo or wmic diskdrive get status.

36. What is the purpose of Windows Event Viewer?

Answer:
It logs system, security, and application events for monitoring and troubleshooting.

37. What is loopback address?

Answer:
127.0.0.1 — used to test the local machine’s network stack.

38. What are user profiles in Windows?

Answer:
A user profile stores settings and data specific to a user account.

39. What is WSUS?

Answer:
Windows Server Update Services manages and distributes Microsoft updates on a network.

40. How do you share a folder with specific users?

Answer:
Right-click folder → Properties → Sharing → Advanced Sharing → Permissions → Add specific users and set access levels.

41. How do you reset Group Policy settings?

Answer:
Run:

cmd
RD /S /Q "%WinDir%\System32\GroupPolicy"
gpupdate /force

42. What is the difference between symmetric and asymmetric encryption?

Answer:

  • Symmetric: One key for encryption/decryption

  • Asymmetric: Public and private keys (e.g., SSL, SSH)

43. What is the role of an IT Administrator?

Answer:
Maintaining systems, network, security, backups, user access, hardware/software support.

44. What is the ping command used for?

Answer:
To test connectivity between two network devices.

45. What’s the use of tracert?

Answer:
It shows the path data takes from source to destination.

46. What is Remote Assistance?

Answer:
A feature allowing another user to remotely view or control your computer with permission.

47. What is a patch?

Answer:
A software update that fixes bugs, vulnerabilities, or adds features.

48. How to schedule automatic shutdown?

Answer:

cmd
shutdown -s -t 3600

49. What is spooler service in Windows?

Answer:
Handles print jobs sent to the printer.

50. What is a proxy server?

Answer:
A server that acts as a gateway between client and internet, often used for control and caching.

51. What is BIOS and UEFI?

Answer:

  • BIOS: Basic Input Output System, older system firmware

  • UEFI: Modern replacement, faster, supports larger drives

52. How to disable a service in Windows?

Answer:
services.msc → Locate service → Right-click → Properties → Set Startup type to Disabled

53. What’s the use of Rsync in Linux?

Answer:
Efficiently syncs files between systems.

54. What is a zero-day vulnerability?

Answer:
A security flaw not yet known to the software vendor, unpatched.

55. What is SSH and its port?

Answer:
Secure Shell, used for secure remote login. Default port: 22

56. What’s the use of the netstat command?

Answer:
To show current network connections, ports in use, and listening services.

57. What is a honeypot in security?

Answer:
A decoy system to lure and analyze attackers.

58. What’s the difference between a full backup and incremental backup?

Answer:

  • Full: Backs up all data

  • Incremental: Backs up only changed data since last backup

59. What is port forwarding?

Answer:
Redirecting traffic from one port to another machine/service behind a firewall.

60. What is NAT?

Answer:
Network Address Translation allows multiple devices to share one public IP.

61. How do you configure Outlook manually?

Answer:
Go to Control Panel > Mail > Email Accounts > New → Enter IMAP/SMTP or Exchange server details.

62. What are .pst and .ost files in Outlook?

Answer:

  • .pst: Personal Storage Table (used in POP3)

  • .ost: Offline Storage Table (used in Exchange/IMAP)

63. What is Sysprep used for?

Answer:
Prepares Windows images for duplication and deployment.

64. What is PXE boot?

Answer:
Preboot Execution Environment – boots a computer using a network interface.

65. What is ITIL?

Answer:
IT Infrastructure Library – framework for managing IT services.

66. What’s a DMZ in networking?

Answer:
Demilitarized Zone – a subnetwork exposed to the internet but isolated from internal systems.

67. How do you secure a Windows server?

Answer:

  • Apply patches

  • Configure firewall

  • Disable unused services

  • Enforce strong passwords

  • Enable auditing and antivirus

68. What is the purpose of SNMP?

Answer:
Simple Network Management Protocol – monitors and manages network devices.

69. What is the difference between reboot and reset?

Answer:

  • Reboot: Restarts the system

  • Reset: Returns system to factory/default settings

70. What is shadow copy?

Answer:
A Windows feature that creates backup copies or snapshots of files or volumes.