DevOps Interview Questions (30+ Questions)

Learn how to identify and manage high I/O consuming processes on a Linux server using command-line tools. This guide covers sorting running processes by disk activity and mitigating disk bottlenecks through throttling, stopping, or rescheduling heavy jobs, improving overall system responsiveness and application performance.

Learn how to safely unmount and remount filesystems to recover from stale handles and inconsistencies using Linux Bash commands. This guide covers identifying low-usage filesystems, checking for active processes, performing safe remount operations, and verifying success, essential for clearing filesystem errors and recovering from storage connectivity issues.

The process count on a production server keeps increasing even though no new workloads were deployed. Zombie processes are accumulating in the system.

Learn how to identify filesystem mount points and diagnose storage-related issues using Linux Bash commands. This guide covers determining which device /var/log resides on, inspecting mount properties, and investigating space constraints, essential for troubleshooting log rotation failures and preventing partition-specific storage exhaustion in production systems.

Learn how to measure disk write performance and select appropriate storage backends using Linux Bash commands. This guide covers benchmarking sequential write speeds, interpreting results, and making data-driven infrastructure decisions, essential for matching storage solutions to application requirements and ensuring performance in data-intensive workloads.

Learn how to identify, format, and mount unmounted partitions on Linux using Bash commands. This guide covers discovering unused block devices, creating filesystems, assigning labels, and temporary mounting, essential for expanding storage capacity, utilizing available hardware resources, and solving storage-related outages in production systems.

Learn how to create symbolic links to centralize file references across application directories using Linux Bash commands. This guide covers linking configuration files, verifying symlink resolution, and enabling transparent access to centralized resources, essential for configuration management, reducing duplication, and maintaining consistency in multi-service deployments.

Learn how to automate continuous vulnerability scanning using Trivy and Bash scripting. This guide covers creating automated scan scripts, filtering severity levels, scheduling daily scans with cron, and generating timestamped reports, essential for maintaining security posture, detecting CVEs early, and implementing DevSecOps practices in production environments.

Enforce user disk usage limits by enabling filesystem quotas and configuring soft/hard limits with grace periods.

Learn how to identify the process writing excessive logs to system files using Linux Bash commands and monitoring tools. This guide covers tracing file handles, monitoring write operations in real time, and pinpointing logging culprits, essential for diagnosing disk space issues, debug logging incidents, and optimizing log management in production systems.

Identify and terminate active user sessions for production maintenance and reboots. Learn how to use w, who, and last commands to identify logged-in users with their terminal, login time, and source IP addresses. This guide covers notifying users of session termination, using pkill or kill to disconnect sessions by terminal, documenting terminated sessions for audit trails, and ensuring maintenance windows proceed without blocking interactive sessions. Essential for emergency maintenance procedures, compliance with deployment scripts, and managing controlled system restarts in production environments.

Learn how to analyze Nginx access logs to identify top traffic sources and dynamically configure rate limiting rules. This guide covers extracting client IP request counts, calculating optimal rate limits based on traffic patterns, and validating Nginx configuration, essential for DDoS mitigation, traffic management, and protecting web servers from aggressive clients.

Learn how to diagnose and resolve disk space exhaustion issues on mounted volumes using Linux Bash commands. This guide covers checking filesystem usage, identifying largest files, freeing storage space, and verifying recovery, essential for troubleshooting storage capacity problems, preventing service failures, and maintaining application availability.

Resolve SSH authentication lockouts caused by exceeding MaxAuthTries limits. Learn how to search authentication logs for failed SSH attempts, count login failures to determine the threshold exceeded, modify /etc/ssh/sshd_config to increase MaxAuthTries, and restart the SSH service to apply changes. This guide covers analyzing /var/log/auth.log for failure patterns, understanding SSH daemon authentication limits, and balancing security with legitimate retry scenarios. Essential for troubleshooting locked-out accounts, debugging CI/CD deployment failures, and maintaining SSH accessibility during key rotation events.

Implement automated log rotation in Linux using logrotate to prevent disk space exhaustion. Learn how to identify oversized log files exceeding size limits, create logrotate configuration files with daily rotation policies, compress archived logs, retain multiple versions for troubleshooting, and implement postrotate scripts to reload application services. This guide covers assessing current log file sizes, configuring retention policies, testing logrotate functionality, and preventing disk-full incidents. Essential for maintaining system stability, preventing production outages from disk space issues, and implementing sustainable log management strategies.

Learn how to inspect, modify, and verify routing table entries on Linux using Bash commands. This guide covers detecting incorrect routes, deleting problematic entries, and adding new routes through specific gateways and interfaces essential for fixing routing misconfigurations and ensuring proper traffic flow in multi-interface networks.

Learn how to query and verify both IPv4 and IPv6 DNS records for a domain using Linux Bash commands. This guide covers resolving A and AAAA records, extracting IP addresses, and creating structured DNS verification reports, essential for diagnosing inconsistent DNS resolution and validating dual-stack network configurations.

Learn how to diagnose network connectivity issues across multiple layers using Bash ping commands. This guide covers testing the default gateway, DNS servers, and external sites to isolate packet loss and latency problems, helping identify whether network issues originate locally, at the ISP, or on the public internet.

Learn how to scan for listening services on specific port ranges and identify their associated processes using Linux Bash commands. This guide covers discovering unauthorized applications on non-standard ports, extracting process IDs, and safely terminating services-essential for security audits and removing unauthorized network listeners.

Learn how to detect and resolve overlapping IPv4 subnets across multiple network interfaces on Linux using Bash commands. This guide covers listing all interface configurations, identifying subnet conflicts, and removing duplicate addresses from lower-priority interfaces while preserving network stability and preventing asymmetric routing issues.

Learn how to add temporary static routes on Linux using Bash commands to reach remote subnets without permanent configuration changes. This guide covers verifying routing tables, adding routes via specific gateways and interfaces, and testing connectivity-essential for emergency network troubleshooting and temporary routing adjustments.

Learn how to capture and analyze HTTP network traffic on port 80 using Bash commands and packet analysis tools. This guide shows how to verify web server connectivity by examining TCP handshakes and packet flow, helping diagnose HTTP communication issues and network configuration problems in production environments.

Learn how to diagnose and resolve MTU mismatch issues in VPN connections using Linux Bash commands. This guide covers inspecting current MTU settings, testing path MTU with the Don't Fragment flag, calculating effective MTU, and adjusting interface settings essential for resolving slow transfers, packet fragmentation, and VPN performance degradation.

Learn how to diagnose DNS resolver configurations across multiple sources on Linux using Bash commands. This guide covers examining /etc/resolv.conf, inspecting systemd-resolved settings, identifying symbolic links, and creating consolidated DNS diagnostics reports, essential for troubleshooting inconsistent domain resolution and split-horizon DNS issues.

Learn how to create robust systemd services with intelligent restart policies using Linux system administration. This guide covers configuring automatic recovery from failures, preventing restart storms with rate limiting, enabling boot persistence, and testing failure scenarios, essential for building resilient services and preventing resource exhaustion in production environments.

Learn how to audit login history and identify after-hours access violations on Linux using Bash commands. This guide covers extracting user login sessions, filtering by time windows, and generating security reports, essential for enforcing access policies, detecting unauthorized logins, and responding to security incidents.

Learn how to create a Bash script that automates connectivity checks for multiple hosts using ping commands. This guide covers reading hostnames from a file, testing reachability, generating status reports, and handling failures gracefully, essential for pre-maintenance validation, network monitoring, and infrastructure health checks in DevOps workflows.