150+ Linux System Administration Interview Questions [Updated 2025]

Linux Fundamentals

1. What is the role of a Linux system administrator?

A Linux system administrator manages servers, ensuring uptime, security, and performance. They handle user accounts, configure file systems, monitor resources, and automate tasks. Beginners use tools like top for monitoring, while advanced admins integrate with Ansible for automation. Test configurations in a VM, monitor logs, and ensure reliable system operations in production environments.

2. Why is Linux preferred for server environments?

Linux’s open-source nature, stability, and flexibility make it ideal for servers. It supports diverse workloads, from web hosting to databases. Configure a test server, monitor with htop, and apply security patches to ensure reliability. Its community-driven updates and compatibility with tools like Docker enhance scalability for enterprise systems.

3. How do you check system resource usage?

Use top or htop to monitor CPU, memory, and processes. Run top, filter processes with ps aux, and log with sar. Test in a VM, analyze output, and automate monitoring with Prometheus to ensure efficient resource management and reliable system performance in production.

4. When should you reboot a Linux server?

Reboot after kernel updates, critical patches, or performance issues like memory leaks. Check uptime, verify running services with systemctl, and schedule reboots during low-traffic periods. Monitor logs post-reboot to ensure services restart correctly, maintaining system stability in production environments.

5. Where do you store system configuration files?

• /etc for system-wide configurations.
• Git repository for version control.
• /etc/sysctl.conf for kernel parameters.
• Monitor changes with auditd.
• Test configs in a VM. Store in Git, automate backups, and ensure consistent system configurations for reliability.

6. Which Linux distributions are common for servers?

• Ubuntu: User-friendly, widely supported.
• CentOS Stream: Stable for enterprises.
• Debian: Lightweight, reliable.
• Red Hat: Commercial support.
• Fedora: Cutting-edge features. Test distros in VMs, monitor performance, and choose based on workload needs.

7. Who performs system maintenance in a team?

Sysadmins perform maintenance, updating packages, monitoring logs, and automating tasks. They test updates in staging, use Git for configurations, and monitor with Prometheus to ensure reliable system performance and consistent operations across enterprise environments.

8. What causes a Linux system to become unresponsive?

• High CPU usage from processes.
• Memory exhaustion or leaks.
• Disk I/O bottlenecks.
• Network congestion.
• Kernel panics. Use top to identify processes, kill with kill -9, and monitor logs to restore system responsiveness.

9. Why is the root user critical in Linux?

The root user has unrestricted access, enabling system-wide changes. Misuse risks security breaches. Use sudo for controlled access, test commands in a VM, and monitor logs with auditd to ensure secure, reliable system administration in production environments.

10. How do you update a Linux system’s packages?

Run apt update && apt upgrade on Ubuntu or yum update on CentOS. Test in a staging VM, schedule updates, and monitor logs for errors. Automate with Ansible to ensure consistent, reliable package updates across multiple servers in production.

User and Group Management

11. What do you do when a user cannot log in?

User login failures disrupt access. Check /etc/passwd for user entry, verify password with passwd, and ensure SSH access. Test login in a VM, monitor logs with journalctl, and update configurations to restore reliable user access in production systems.

12. Why does a user fail to execute sudo commands?

Sudo failures occur due to missing sudoers permissions or syntax errors. Validate /etc/sudoers with visudo, add user to sudo group, and test in a VM. Monitor logs to ensure secure, reliable sudo access for administrative tasks in production.

13. How do you create a new user with specific permissions?

useradd -m -s /bin/bash newuser
passwd newuser
usermod -aG sudo newuser
Test login, verify permissions with id, and monitor logs to ensure reliable user creation and secure access in production environments.

14. When should you lock a user account?

Lock accounts for security during employee offboarding or suspicious activity. Use passwd -l username, verify with /etc/shadow, and test in a VM. Monitor audit logs to ensure compliance and secure account management in production systems.

15. Where do you store user account details?

• /etc/passwd for user metadata.
• /etc/shadow for encrypted passwords.
• /etc/group for group memberships.
• Audit logs for tracking changes.
• Git for configuration backups. Store securely, test in a VM, and ensure reliable user management.

16. Which commands manage user groups?

• groupadd: Creates new groups.
• usermod -aG: Adds users to groups.
• groupdel: Deletes groups.
• getent group: Lists group members.
• id: Verifies memberships. Test in a VM, monitor logs for reliable group management.

17. Who manages user accounts in a Linux environment?

Sysadmins manage user accounts, creating users with useradd, setting permissions, and auditing access. They test in staging, automate with scripts, and monitor with auditd to ensure secure, reliable user management in production environments.

18. What causes a user to lose file access?

• Incorrect file permissions.
• Missing group memberships.
• SELinux context issues.
• Filesystem corruption.
• Ownership mismatches. Check with ls -l, update with chmod/chown, and monitor logs for reliable access restoration.

19. Why is sudo preferred over root login?

Sudo provides controlled access, reducing security risks compared to root login. Configure /etc/sudoers with visudo, test in a VM, and monitor audit logs to ensure secure, auditable administrative actions in production environments.

20. How do you remove a user and their files?

userdel -r username
Verify with /etc/passwd, check for residual files, and test in a VM. Monitor logs with journalctl to ensure complete removal and compliance with security policies in production systems.

File Systems and Storage

21. What do you do when a filesystem is full?

A full filesystem halts operations. Check usage with df -h, identify large files with du -sh, and delete or archive unneeded data. Test in a VM, expand storage if needed, and monitor with Prometheus to restore reliable filesystem operations in production.

22. Why does a filesystem become corrupted?

Filesystem corruption results from power failures, disk errors, or improper shutdowns. Run fsck /dev/sdX to repair, back up data, and test in a VM. Monitor logs to prevent recurrence and ensure reliable filesystem integrity in production environments.

23. How do you create an ext4 filesystem?

mkfs.ext4 /dev/sdX
Mount with mount /dev/sdX /mnt, update /etc/fstab, and test in a VM. Monitor logs with journalctl to ensure reliable filesystem creation and consistent storage management in production environments.

24. When should you use LVM for storage?

Use LVM for dynamic resizing and snapshots in dynamic environments. Create with pvcreate, vgcreate, and lvcreate, test in a VM, and monitor with lvs. Automate with Ansible for reliable, scalable storage management in production systems.

25. Where do you store filesystem configurations?

• /etc/fstab for mount points.
• Git repository for version control.
• /etc/lvm for LVM settings.
• Monitor with Prometheus for metrics.
• Test in a VM for reliability. Store in Git, automate backups, and ensure consistent storage configs.

26. Which tools manage disk partitions?

• fdisk: Creates and edits partitions.
• parted: Handles advanced partitioning.
• lsblk: Lists block devices.
• mkfs: Formats filesystems.
• df: Monitors usage. Test in a VM, monitor logs for reliable partition management.

27. Who manages storage in a Linux environment?

Sysadmins manage storage, configuring filesystems and LVM. They test in staging, automate with Ansible, and monitor with Prometheus to ensure reliable storage management and consistent performance across enterprise systems in production.

28. What causes a filesystem mount failure?

• Incorrect /etc/fstab entries.
• Missing device or UUID.
• Filesystem corruption.
• Insufficient permissions.
• Hardware issues. Validate with mount -a, test in a VM, and monitor logs for reliable mounts.

29. Why is LVM preferred for enterprise storage?

LVM allows dynamic resizing and snapshots, enhancing flexibility. Configure with pvcreate/vgcreate, test in a VM, and monitor with lvs. Automate with Ansible to ensure scalable, reliable storage management in enterprise production environments.

30. How do you extend an LVM logical volume?

lvextend -L +10G /dev/vgname/lvname
resize2fs /dev/vgname/lvname
Test in a VM, verify with lvs, and monitor logs to ensure reliable volume extension and consistent storage management in production systems.

Networking

31. What do you do when a server loses network connectivity?

Network loss disrupts services. Check interfaces with ip link, verify configs in /etc/network, and test with ping. Restart networking with systemctl, monitor logs with journalctl, and ensure reliable connectivity restoration in production environments.

32. Why does a server fail to resolve DNS queries?

DNS failures stem from incorrect /etc/resolv.conf or network issues. Validate nameservers, test with dig, and update configurations. Monitor logs and test in a VM to ensure reliable DNS resolution and network stability in production systems.

33. How do you configure a static IP address?

Edit /etc/network/interfaces:
auto eth0
iface eth0 inet static
address 192.168.1.100
netmask 255.255.255.0
gateway 192.168.1.1
Restart networking, test with ip addr, and monitor logs for reliable IP configuration.

34. When should you use iptables for firewall rules?

Use iptables for granular network security in legacy systems. Define rules with iptables -A, test in a VM, and monitor with iptables -L. Automate with Ansible for reliable, consistent firewall management in production environments.

35. Where do you store network configurations?

• /etc/network for interface settings.
• /etc/resolv.conf for DNS.
• Git repository for version control.
• Monitor with Prometheus for metrics.
• Test in a VM for reliability. Store in Git, automate updates, and ensure consistent networking.

36. Which tools monitor network traffic?

• tcpdump: Captures packets.
• Wireshark: Analyzes traffic.
• iftop: Monitors bandwidth.
• netstat: Lists connections.
• Prometheus: Tracks metrics. Test in a VM, monitor logs for reliable network performance.

37. Who configures networking in a team?

Sysadmins configure networking, setting IPs and firewalls. They test in staging, automate with Ansible, and monitor with Prometheus to ensure reliable network performance and consistent connectivity across enterprise systems in production.

38. What causes a network interface to go down?

• Hardware failures in NIC.
• Incorrect interface configurations.
• Network cable issues.
• Driver incompatibilities.
• Power disruptions. Check with ip link, test in a VM, and monitor logs for reliable restoration.

39. Why is firewalld preferred over iptables?

Firewalld provides dynamic rule management, simplifying updates. Configure with firewall-cmd, test in a VM, and monitor logs. Automate with Ansible to ensure reliable, scalable firewall management in modern production environments.

40. How do you capture network traffic for analysis?

tcpdump -i eth0 -w capture.pcap
Analyze with Wireshark, test in a VM, and monitor logs to ensure reliable traffic capture and network troubleshooting in production environments.

Security

41. What do you do when a server is compromised?

A compromised server risks data loss. Isolate with iptables, analyze logs with journalctl, and remove malicious processes. Update passwords, patch vulnerabilities, and test in a VM. Monitor with Prometheus to restore secure, reliable operations in production.

42. Why does SSH access fail for a user?

SSH failures result from incorrect keys or configurations. Validate ~/.ssh/authorized_keys, check /etc/ssh/sshd_config, and test with ssh -v. Monitor logs with journalctl to ensure secure, reliable SSH access restoration in production systems.

43. How do you harden a Linux server?

Disable root login in /etc/ssh/sshd_config:
PermitRootLogin no
Use SSH keys, update packages, and enable SELinux. Test in a VM, monitor with auditd, and automate with Ansible for reliable server hardening in production.

44. When should you enable SELinux?

Enable SELinux for enhanced security in sensitive environments. Set to enforcing in /etc/selinux/config, test in a VM, and monitor logs with auditd. Automate with Ansible for reliable, compliant security in production systems.

45. Where do you store SSH keys securely?

• ~/.ssh for user keys.
• /etc/ssh for host keys.
• Git repository for backups.
• Monitor access with auditd.
• Test in a VM for reliability. Store securely, automate updates, and ensure secure access.

46. Which tools enhance Linux security?

• SELinux: Enforces access controls.
• fail2ban: Blocks brute-force attacks.
• auditd: Tracks system activity.
• ClamAV: Scans for malware.
• Prometheus: Monitors security metrics. Test in a VM, ensure reliable security.

47. Who manages server security in a team?

Security admins manage server security, configuring SELinux and SSH. They test in staging, automate with Ansible, and monitor with Prometheus to ensure secure, reliable system operations in production environments.

48. What prevents unauthorized SSH access?

• SSH key-based authentication.
• Disabling root login.
• fail2ban for brute-force protection.
• Firewall rules with iptables.
• Monitoring with Prometheus. Configure in /etc/ssh/sshd_config, test in a VM, and ensure security.

49. Why does SELinux block legitimate processes?

SELinux blocks processes due to incorrect contexts or policies. Check with sestatus, update contexts with chcon, and test in a VM. Monitor logs with auditd to ensure reliable process execution and security in production.

50. How do you configure fail2ban for SSH protection?

Edit /etc/fail2ban/jail.local:
[sshd]
enabled = true
maxretry = 5
bantime = 3600
Test with fail2ban-client, monitor logs, and ensure reliable brute-force protection in production.

Scripting and Automation

51. What do you do when a Bash script fails to execute?

Script failures disrupt automation. Check syntax with bash -n script.sh, verify permissions with chmod +x, and test in a VM. Monitor logs with journalctl to debug and ensure reliable script execution in production environments.

52. Why does a cron job fail to run?

Cron job failures result from incorrect crontab syntax or permissions. Validate with crontab -l, check logs in /var/log/syslog, and test in a VM. Update crontab and monitor to ensure reliable scheduled task execution in production.

53. How do you write a Bash script to monitor disk usage?

#!/bin/bash
df -h | grep /dev/sdX | awk '{print $5}' > /tmp/disk_usage.txt
Test in a VM, schedule with cron, and monitor logs to ensure reliable disk usage tracking in production systems.

54. When should you use Ansible for automation?

Use Ansible for scalable, repeatable tasks like package updates. Write playbooks, test in a VM, and monitor with Prometheus. Automate with Ansible for reliable, consistent configuration management across enterprise systems in production.

55. Where do you store automation scripts?

• Git repository for version control.
• /usr/local/bin for scripts.
• /etc/cron.d for cron jobs.
• Monitor with Prometheus for metrics.
• Test in a VM for reliability. Store in Git, ensure consistent automation workflows.

56. Which scripting languages are used in Linux?

• Bash: For system automation.
• Python: For complex scripts.
• Perl: For text processing.
• Shell: For simple tasks.
• Ansible: For configuration management. Test in a VM, monitor logs for reliability.

57. Who writes automation scripts in a team?

Sysadmins write automation scripts, using Bash or Python. They test in staging, commit to Git, and monitor with Prometheus to ensure reliable automation and consistent system management in production environments.

58. What causes a script to consume excessive CPU?

• Infinite loops in code.
• Inefficient command usage.
• Large data processing.
• Unoptimized algorithms.
• Lack of monitoring. Debug with top, test in a VM, and monitor with Prometheus for efficiency.

59. Why is Python preferred for automation scripts?

Python’s readability and libraries enhance automation. Use Python for tasks like log parsing, test in a VM, and monitor with Prometheus. Automate with Ansible for reliable, scalable script execution in production environments.

60. How do you schedule a cron job for daily backups?

crontab -e
0 2 * * * /backup.sh
Test in a VM, verify with crontab -l, and monitor logs to ensure reliable daily backups in production systems.

System Monitoring

61. What do you do when a server has high CPU usage?

High CPU usage slows systems. Identify processes with top, kill with kill -9, and analyze with sar. Test in a VM, optimize processes, and monitor with Prometheus to restore reliable performance in production environments.

62. Why does a server experience memory leaks?

Memory leaks result from buggy processes or unoptimized scripts. Check with free -m, identify culprits with top, and restart services. Test in a VM, monitor with Prometheus, and ensure reliable memory management in production systems.

63. How do you monitor disk I/O performance?

iostat -x 1
Analyze output, identify bottlenecks, and test in a VM. Monitor with Prometheus and automate alerts to ensure reliable disk performance and system stability in production environments.

64. When should you use Prometheus for monitoring?

Use Prometheus for real-time metrics in large environments. Configure with prometheus.yml, test in a VM, and integrate with Grafana. Automate alerts to ensure reliable system monitoring and performance in production systems.

65. Where do you store monitoring configurations?

• /etc/prometheus for Prometheus configs.
• Git repository for version control.
• /var/log for monitoring logs.
• Grafana for visualization configs.
• Test in a VM for reliability. Store in Git, ensure consistent monitoring setups.

66. Which tools monitor system performance?

• top: Real-time process monitoring.
• htop: Interactive process viewer.
• sar: Collects system metrics.
• Prometheus: Tracks real-time data.
• Grafana: Visualizes metrics. Test in a VM, ensure reliable performance monitoring.

67. Who monitors system performance in a team?

Sysadmins monitor performance, using top and Prometheus. They test in staging, automate alerts, and integrate with Grafana to ensure reliable system performance and consistent monitoring in production environments.

68. What causes high disk I/O on a server?

• Large file transfers.
• Database queries.
• Log rotation issues.
• Filesystem fragmentation.
• Insufficient RAM. Check with iostat, optimize processes, and monitor with Prometheus for reliability.

69. Why does monitoring fail to detect issues?

Monitoring failures occur due to incorrect configurations or thresholds. Validate prometheus.yml, test in a VM, and update alert rules. Monitor with Prometheus to ensure reliable issue detection in production environments.

70. How do you set up Prometheus for monitoring?

Install Prometheus, configure prometheus.yml:
global:
scrape_interval: 15s
scrape_configs:

• job_name: 'node'
  static_configs:
  • targets: ['localhost:9100']
    Test in a VM, monitor with Grafana for reliable system monitoring.

Troubleshooting

71. What do you do when a service fails to start?

Service failures disrupt operations. Check status with systemctl status, analyze logs with journalctl, and verify configs. Test in a VM, restart service, and monitor with Prometheus to restore reliable service operations in production.

72. Why does a server fail to boot?

Boot failures result from corrupted kernels or GRUB issues. Check /boot/grub/grub.cfg, boot from a rescue disk, and repair with fsck. Test in a VM, monitor logs for reliable boot restoration in production systems.

73. How do you troubleshoot a network connectivity issue?

ping 8.8.8.8
traceroute google.com
Check /etc/resolv.conf, test in a VM, and monitor with journalctl to restore reliable network connectivity in production environments.

74. When does a server require log analysis?

• Service failures occur.
• Performance issues detected.
• Security incidents reported.
• System crashes logged.
• Monitoring alerts triggered. Analyze with journalctl, test in a VM, and monitor for reliability.

75. Where do you find system logs?

• /var/log/syslog for system events.
• /var/log/auth.log for authentication.
• /var/log/kern.log for kernel issues.
• journalctl for systemd logs.
• Prometheus for metrics. Analyze logs, test in a VM, and ensure reliable troubleshooting.

76. Which tools aid system troubleshooting?

• journalctl: Views systemd logs.
• dmesg: Checks kernel messages.
• tcpdump: Captures network traffic.
• strace: Traces system calls.
• Prometheus: Monitors metrics. Test in a VM, ensure reliable issue resolution.

77. Who troubleshoots system issues in a team?

Sysadmins troubleshoot issues, analyzing logs with journalctl and optimizing configs. They test in staging, automate fixes with Ansible, and monitor with Prometheus to ensure reliable system operations in production environments.

78. What causes a process to hang indefinitely?

• Resource contention (CPU, memory).
• Deadlocks in applications.
• I/O bottlenecks.
• Kernel issues.
• Insufficient swap. Check with top, kill process, and monitor with Prometheus for reliability.

79. Why does a server crash unexpectedly?

Crashes result from kernel panics or hardware failures. Check dmesg, update drivers, and test in a VM. Monitor with Prometheus to prevent recurrence and ensure reliable system stability in production environments.

80. How do you debug a failing cron job?

crontab -l
tail -f /var/log/syslog
Test script in a VM, fix syntax, and monitor logs to ensure reliable cron job execution in production systems.

Automation with Ansible

81. What do you do when an Ansible playbook fails?

Playbook failures disrupt automation. Use ansible-playbook --syntax-check, fix YAML errors, and test in a VM. Update playbook, rerun, and monitor with Prometheus to restore reliable automation in production environments.

82. Why does an Ansible module fail to execute?

Module failures result from incorrect parameters or missing dependencies. Validate with ansible-doc, update YAML, and test in a VM. Monitor logs to ensure reliable module execution and automation stability in production systems.

83. How do you automate package updates with Ansible?

• hosts: all
  tasks:
  • name: Update packages
    apt:
    update_cache: yes
    upgrade: dist

Test in a VM, automate with ansible-playbook, and monitor logs for reliable updates.

84. When should you use Ansible roles?

Use roles for reusable, modular automation. Create roles/role/tasks/main.yml, test in a VM, and monitor with Prometheus. Include in playbooks for reliable, scalable configuration management in production environments.

85. Where do you store Ansible playbooks?

• Git repository for version control.
• /etc/ansible for playbooks.
• GitHub for team access.
• Monitor with Prometheus for metrics.
• Test in a VM for reliability. Store in Git, ensure consistent automation workflows.

86. Which Ansible modules are used for Linux administration?

• apt: Manages Debian packages.
• yum: Manages Red Hat packages.
• service: Controls services.
• file: Manages filesystems.
• user: Manages accounts. Test in a VM, monitor logs for reliable automation.

87. Who manages Ansible automation in a team?

DevOps engineers manage Ansible, writing playbooks and testing in VMs. They commit to Git, automate with scripts, and monitor with Prometheus to ensure reliable configuration management in production environments.

88. What causes an Ansible playbook to fail on specific hosts?

• Connectivity issues to hosts.
• Incorrect inventory settings.
• Missing module dependencies.
• Permission errors.
• Invalid YAML syntax. Test with ansible -m ping, monitor logs for reliable execution.

89. Why is Ansible Vault used in automation?

Ansible Vault encrypts sensitive data, ensuring security. Create vaulted files with ansible-vault create, test in a VM, and monitor logs. Automate with Ansible for secure, reliable configuration management in production environments.

90. How do you use Ansible to manage users?

• hosts: all
  tasks:
  • name: Create user
    user:
    name: appuser
    state: present

Test in a VM, automate with ansible-playbook, and monitor logs for reliable user management.

Containerization and Cloud

91. What do you do when a Docker container fails to start?

Container failures disrupt services. Check with docker ps -a, inspect logs with docker logs, and verify Dockerfile. Test in a VM, restart container, and monitor with Prometheus to restore reliable container operations in production.

92. Why does a Kubernetes pod fail to deploy?

Pod failures result from incorrect YAML or resource limits. Validate with kubectl describe pod, update manifests, and test in a minikube cluster. Monitor with Prometheus for reliable Kubernetes deployments in production environments.

93. How do you deploy a Docker container on Linux?

docker run -d -p 80:80 nginx
Verify with docker ps, test in a VM, and monitor logs with journalctl to ensure reliable container deployment in production systems.

94. When should you use Kubernetes on Linux?

Use Kubernetes for orchestrating containers in scalable environments. Deploy with minikube, test in a VM, and monitor with Prometheus. Automate with Ansible for reliable, scalable container management in production systems.

95. Where do you store Docker configurations?

• /etc/docker for daemon settings.
• Git repository for Dockerfiles.
• /var/lib/docker for images.
• Monitor with Prometheus for metrics.
• Test in a VM for reliability. Store in Git, ensure consistent container configs.

96. Which tools manage containers on Linux?

• Docker: Runs containers.
• Kubernetes: Orchestrates containers.
• Podman: Rootless container management.
• docker-compose: Manages multi-containers.
• Prometheus: Monitors metrics. Test in a VM, ensure reliable container operations.

97. Who manages containers in a team?

DevOps engineers manage containers, deploying with Docker and Kubernetes. They test in staging, automate with Ansible, and monitor with Prometheus to ensure reliable container operations in production environments.

98. What causes a container to crash unexpectedly?

• Insufficient memory or CPU.
• Application errors in code.
• Incorrect Dockerfile settings.
• Network connectivity issues.
• Storage limitations. Check with docker logs, test in a VM, and monitor for reliability.

99. Why is Podman used instead of Docker?

Podman’s rootless architecture enhances security. Run podman run nginx, test in a VM, and monitor logs. Automate with Ansible for reliable, secure container management in production environments without requiring a daemon.

100. How do you integrate Linux with AWS EC2?

Configure AWS CLI with aws configure, launch EC2 instances, and manage with Ansible. Test in a VM, monitor with CloudWatch, and automate for reliable cloud integration in production environments.

Performance Tuning

101. What do you do when a server has high latency?

High latency impacts performance. Check with top, analyze network with tcpdump, and optimize processes. Test in a VM, tune kernel with sysctl, and monitor with Prometheus to restore reliable system performance in production.

102. Why does a server experience slow disk performance?

Slow disk performance results from I/O bottlenecks or fragmentation. Check with iostat, defragment with e2fsck, and test in a VM. Monitor with Prometheus to ensure reliable disk performance and system stability in production.

103. How do you tune kernel parameters for performance?

Edit /etc/sysctl.conf:
vm.swappiness=10
Apply with sysctl -p, test in a VM, and monitor with Prometheus to ensure reliable performance tuning in production systems.

104. When should you optimize server performance?

• High latency reported.
• Resource usage spikes.
• Application slowdowns detected.
• Monitoring alerts triggered.
• Performance bottlenecks identified. Tune with sysctl, test in a VM, and monitor for reliability.

105. Where do you store performance configurations?

• /etc/sysctl.conf for kernel settings.
• Git repository for version control.
• /etc/tuned for profiles.
• Monitor with Prometheus for metrics.
• Test in a VM for reliability. Store in Git, ensure consistent performance configs.

106. Which tools optimize Linux performance?

• sysctl: Tunes kernel parameters.
• tuned: Applies performance profiles.
• cpupower: Manages CPU frequency.
• iostat: Monitors disk performance.
• Prometheus: Tracks metrics. Test in a VM, ensure reliable performance tuning.

107. Who tunes server performance in a team?

Sysadmins tune performance, adjusting kernel settings and monitoring with Prometheus. They test in staging, automate with Ansible, and ensure reliable system performance and stability in production environments.

108. What causes high swap usage on a server?

• Insufficient RAM for processes.
• Memory-intensive applications.
• Incorrect swappiness settings.
• Leaking processes.
• Monitoring gaps. Check with free -m, tune swappiness, and monitor with Prometheus for reliability.

109. Why does performance degrade over time?

Performance degradation results from resource leaks or unoptimized configs. Monitor with sar, update kernel parameters, and test in a VM. Automate with Ansible for reliable, sustained performance in production environments.

110. How do you optimize CPU usage on a server?

nice -n 10 command
cpupower frequency-set -g performance
Test in a VM, monitor with Prometheus, and ensure reliable CPU optimization in production systems.

Backup and Recovery

111. What do you do when a backup fails to complete?

Backup failures risk data loss. Check logs in /var/log, verify storage with df -h, and test script in a VM. Fix permissions, rerun backup, and monitor with Prometheus to ensure reliable data protection in production.

112. Why does a server fail to restore from backup?

Restore failures result from corrupted backups or incompatible formats. Validate with tar -tvf, test in a VM, and monitor logs. Ensure backup integrity to restore reliable data recovery in production environments.

113. How do you create a full system backup?

tar -cvzf /backup/full_backup.tar.gz / --exclude=/proc
Test in a VM, schedule with cron, and monitor logs to ensure reliable full system backups in production environments.

114. When should you test backup restores?

• After major system updates.
• Post-backup creation.
• During disaster recovery drills.
• When storage issues occur.
• Compliance audits scheduled. Test in a VM, monitor logs for reliable recovery.

115. Where do you store backup files?

• /backup for local storage.
• Git repository for scripts.
• AWS S3 for offsite backups.
• Monitor with Prometheus for metrics.
• Test in a VM for reliability. Store securely, ensure consistent backup management.

116. Which tools manage Linux backups?

• tar: Archives filesystems.
• rsync: Syncs data incrementally.
• Bacula: Enterprise backup solution.
• Duplicity: Encrypted backups.
• Prometheus: Monitors backup metrics. Test in a VM, ensure reliable backups.

117. Who manages backups in a team?

Sysadmins manage backups, scheduling with cron and testing in VMs. They automate with Ansible, monitor with Prometheus, and ensure reliable data protection and recovery in production environments.

118. What causes a backup to become corrupted?

• Storage device failures.
• Interrupted backup processes.
• Insufficient disk space.
• Network transfer errors.
• Lack of validation. Check with tar -tvf, test in a VM, and monitor for reliability.

119. Why is incremental backup preferred?

Incremental backups save time and storage by backing up changes only. Use rsync, test in a VM, and monitor with Prometheus. Automate with Ansible for reliable, efficient backup management in production environments.

120. How do you restore a file from a backup?

tar -xvzf /backup/backup.tar.gz -C /restore
Verify with ls, test in a VM, and monitor logs to ensure reliable file restoration in production systems.

Advanced Scenarios

121. What do you do when a kernel panic occurs?

Kernel panics halt systems. Boot from a rescue disk, check /var/log/kern.log, and update kernel. Test in a VM, monitor with Prometheus, and ensure reliable system stability in production environments.

122. Why does a server fail to join a cluster?

Cluster join failures result from network or configuration issues. Validate /etc/hosts, check cluster status with corosync, and test in a VM. Monitor logs for reliable cluster integration in production systems.

123. How do you configure a high-availability cluster?

Install pacemaker and corosync:
crm configure property stonith-enabled=false
Test in a VM, monitor with crm_mon, and ensure reliable high-availability in production systems.

124. When should you use containers over VMs?

Use containers for lightweight, portable applications. Deploy with Docker, test in a VM, and monitor with Prometheus. Automate with Ansible for reliable, scalable container management in production environments.

125. Where do you store cluster configurations?

• /etc/corosync for cluster settings.
• Git repository for version control.
• /etc/pacemaker for HA configs.
• Monitor with Prometheus for metrics.
• Test in a VM for reliability. Store in Git, ensure consistent cluster configs.

126. Which tools manage Linux clusters?

• Pacemaker: Manages high availability.
• Corosync: Handles cluster messaging.
• DRBD: Replicates storage.
• crmsh: Configures clusters.
• Prometheus: Monitors metrics. Test in a VM, ensure reliable cluster operations.

127. Who manages clusters in a team?

Sysadmins manage clusters, configuring pacemaker and testing in VMs. They automate with Ansible, monitor with Prometheus, and ensure reliable high-availability operations in production environments.

128. What causes a cluster node to fail?

• Network connectivity issues.
• Resource exhaustion.
• Corosync misconfigurations.
• Storage replication failures.
• Monitoring gaps. Check with crm_mon, test in a VM, and monitor for reliability.

129. Why does a containerized app fail to scale?

Scaling failures result from resource limits or network issues. Validate Docker limits, update Kubernetes YAML, and test in a minikube cluster. Monitor with Prometheus for reliable scaling in production environments.

130. How do you implement log rotation for large logs?

Edit /etc/logrotate.d/app:
/var/log/app.log {
daily
rotate 7
compress
}
Test with logrotate -f, monitor logs for reliable rotation in production.

Compliance and Auditing

131. What do you do when a server fails a compliance audit?

Compliance failures risk penalties. Check auditd logs, update SELinux policies, and test in a VM. Automate with Ansible, monitor with Prometheus, and ensure compliant, secure operations in production environments.

132. Why does a server fail to log audit events?

Audit failures result from disabled auditd or incorrect rules. Validate /etc/audit/audit.rules, enable auditd, and test in a VM. Monitor logs to ensure reliable auditing and compliance in production systems.

133. How do you configure auditd for compliance?

Edit /etc/audit/audit.rules:
-w /etc/passwd -p wa -k passwd_changes
Enable auditd, test in a VM, and monitor logs to ensure reliable auditing in production systems.

134. When should you perform a security audit?

• Post-security incidents.
• Regulatory reviews scheduled.
• New compliance requirements.
• System configuration changes.
• Monitoring alerts triggered. Test in a VM, monitor logs for compliance.

135. Where do you store audit logs?

• /var/log/audit for auditd logs.
• Git repository for configurations.
• CloudWatch for centralized logging.
• Monitor with Prometheus for metrics.
• Test in a VM for reliability. Store securely, ensure consistent auditing.

136. Which tools enforce compliance in Linux?

• auditd: Tracks system events.
• SELinux: Enforces access controls.
• ClamAV: Scans for malware.
• Lynis: Audits security.
• Prometheus: Monitors compliance metrics. Test in a VM, ensure reliable compliance.

137. Who manages compliance in a team?

Security admins manage compliance, configuring auditd and SELinux. They test in staging, automate with Ansible, and monitor with Prometheus to ensure compliant, secure operations in production environments.

138. What ensures server compliance with policies?

• SELinux for access control.
• auditd for event logging.
• Regular security patches.
• Ansible for automated configs.
• Prometheus for compliance metrics. Test in a VM, ensure reliable compliance.

139. Why does a server fail to meet compliance standards?

Compliance failures stem from unpatched systems or missing logs. Update packages, enable auditd, and test in a VM. Monitor with Prometheus to ensure compliant, secure operations in production environments.

140. How do you automate compliance scans?

Install Lynis:
lynis audit system
Schedule with cron, test in a VM, and monitor with Prometheus to ensure reliable, automated compliance scanning in production systems.

Cloud and Virtualization

141. What do you do when a VM fails to start?

VM failures disrupt services. Check logs with journalctl, verify configs in /etc/libvirt, and test in a VM. Restart libvirtd, monitor with Prometheus, and ensure reliable VM operations in production environments.

142. Why does a cloud instance fail to connect?

Connection failures result from incorrect security groups or SSH settings. Validate AWS security groups, check ~/.ssh, and test with ssh -v. Monitor logs for reliable cloud connectivity in production systems.

143. How do you deploy a VM with KVM?

virt-install --name testvm --ram 1024 --disk size=10 --os-type linux
Test with virsh list, monitor logs, and ensure reliable VM deployment in production environments.

144. When should you use cloud over on-premises servers?

Use cloud for scalability and flexibility. Deploy with AWS EC2, test in a VM, and monitor with CloudWatch. Automate with Ansible for reliable cloud management in production environments.

145. Where do you store VM configurations?

• /etc/libvirt for KVM configs.
• Git repository for version control.
• /var/lib/libvirt for images.
• Monitor with Prometheus for metrics.
• Test in a VM for reliability. Store in Git, ensure consistent VM configs.

146. Which tools manage virtualization on Linux?

• KVM: Hypervisor for VMs.
• libvirt: Manages VMs.
• virt-install: Deploys VMs.
• VirtualBox: Desktop virtualization.
• Prometheus: Monitors metrics. Test in a VM, ensure reliable virtualization.

147. Who manages cloud instances in a team?

DevOps engineers manage cloud instances, deploying with AWS and testing in VMs. They automate with Ansible, monitor with CloudWatch, and ensure reliable cloud operations in production environments.

148. What causes a cloud instance to fail provisioning?

• Incorrect IAM permissions.
• Invalid AMIs or configs.
• Network security group issues.
• Quota limits reached.
• Connectivity errors. Validate with aws cli, test in a VM, and monitor for reliability.

149. Why is containerization preferred for microservices?

Containerization offers lightweight, portable deployments. Use Docker, test in a VM, and monitor with Prometheus. Automate with Ansible for reliable, scalable microservices management in production environments.

150. How do you integrate Linux with Azure?

Configure Azure CLI with az login, deploy VMs, and manage with Ansible. Test in a VM, monitor with Azure Monitor, and automate for reliable cloud integration in production environments.

Disaster Recovery

151. What do you do when a server loses critical data?

Data loss disrupts operations. Restore from backups with tar -xvzf, verify integrity, and test in a VM. Monitor with Prometheus, automate recovery with Ansible, and ensure reliable data restoration in production.

152. Why does a recovery process fail?

Recovery failures result from corrupted backups or misconfigurations. Validate backups with tar -tvf, test in a VM, and monitor logs. Ensure backup integrity for reliable data recovery in production environments.

153. How do you implement a disaster recovery plan?

Create backups with rsync, store in S3, and test restores in a VM. Automate with Ansible, monitor with Prometheus, and ensure reliable disaster recovery in production environments.