Essential System Administrator Interview Questions (and Answers!)

Landing a system administrator role requires a solid understanding of operating systems, networking, and security. To help you prepare, we've compiled a list of common interview questions and comprehensive answers. Whether you're a seasoned admin or just starting your career, this guide will help you showcase your expertise.

Core Responsibilities and System Fundamentals

1. What are the responsibilities of a system administrator?

A system administrator is the backbone of any IT infrastructure. They're responsible for installing, configuring, and maintaining computer systems, servers, and networks. This includes tasks like:

• User Management: Creating, deleting, and managing user accounts.

• Security Updates: Ensuring systems are patched and protected from vulnerabilities.

• Backups and Recovery: Implementing backup strategies to protect critical data.

• Performance Monitoring: Tracking system performance and identifying bottlenecks.

• Troubleshooting: Resolving hardware and software issues.

• Uptime Assurance: Maintaining system availability and minimizing downtime.

2. What is the difference between a process and a thread?

• A process is an independent program in execution, with its own dedicated memory space. Think of it as a separate, self-contained application.

• A thread is a lightweight unit of execution within a process. Multiple threads can exist within a single process, sharing the same memory space. This allows for concurrent execution of tasks within a program.

3. What are the different types of operating systems you have worked on?

System administrators should be familiar with a variety of operating systems. Common examples include:

• Windows Server (e.g., 2016, 2019, 2022)

• Linux Distributions (e.g., Ubuntu, CentOS, RHEL)

• Unix-based OS (e.g., Solaris, AIX)

4. How do you check the system uptime in Linux and Windows?

• Linux: Use the uptime command or read the /proc/uptime file.

• Windows: Use the command systeminfo | find "System Boot Time" or net stats srv.

5. How do you check CPU and memory usage in Linux?

• For real-time monitoring: top or htop.

• For memory usage: free -m.

• For CPU statistics: vmstat or mpstat.

6. How do you check disk space usage in Linux and Windows?

• Linux: df -h (disk usage), du -sh <directory> (directory size).

• Windows: wmic logicaldisk get size,freespace,caption.

User and Permission Management

7. How do you create a new user in Linux and Windows?

• Linux: useradd username and set a password with passwd username.

• Windows: net user username password /add.

8. How do you change file permissions in Linux?

Use the chmod command:

• chmod 755 filename (read, write, execute for owner; read, execute for others).

• chmod -R 777 directory/ (full access for all users in the directory and its subdirectories).

9. How do you check which users are currently logged in?

• Linux: who or w.

• Windows: query user.

Networking and Troubleshooting

10. How do you check the IP address of a system?

• Linux: ip a or ifconfig.

• Windows: ipconfig.

11. How do you check if a server is reachable?

• Use the ping command: ping <IP Address>.

• Use the traceroute command: traceroute <IP> (Linux) or tracert <IP> (Windows).

12. What are common ports used in networking?

• HTTP: 80

• HTTPS: 443

• SSH: 22

• FTP: 21

• RDP: 3389

13. How do you restart a service in Linux and Windows?

• Linux: systemctl restart service_name or service service_name restart.

• Windows: net stop service_name & net start service_name.

Backup and Security

14. How do you take a backup of a directory in Linux?

Use the tar command: tar -czvf backup.tar.gz /path/to/directory.

15. How do you schedule a cron job in Linux?

Use crontab -e and add a cron job, for example: 0 2 * * * /path/to/script.sh (runs the script at 2:00 AM daily).

Key Takeaways

• Thoroughly understand the fundamentals of operating systems and networking.

• Practice common system administration tasks in both Linux and Windows environments.

• Be prepared to discuss your experience with backup and security best practices.

• Be ready to explain your troubleshooting methodologies.

By mastering these questions and concepts, you'll be well on your way to acing your system administrator interview!