Comprehensive knowledge of operating system concepts and practical administration across Linux, Unix, and Windows platforms. Core theoretical topics include processes and threads, process creation and termination, scheduling and context switching, synchronization and deadlock conditions, system calls, kernel versus user space, interrupt handling, memory management including virtual memory, paging and swapping, and input and output semantics including file descriptors. Practical administration and tooling expectations include file systems and permission models, user and group account management, common system utilities and commands such as grep, find, ps, and top, package management, service and process management, startup and boot processes, environment variables, shell and scripting basics, system monitoring, and performance tuning. Platform specific knowledge should cover Unix and Linux topics such as signals and signal handling, kernel modules, initialization and service management systems, and command line administration, as well as Windows topics such as the registry, service management, event logs, user account control, and graphical and command line administration tools. Security and infrastructure topics include basic system hardening, common misconfigurations, and an understanding of containerization and virtualization at the operating system level. Interview questions may probe conceptual explanations, platform comparisons, troubleshooting scenarios, or hands on problem solving.
HardTechnical
76 practiced
Describe virtual memory internals: page tables, Translation Lookaside Buffer (TLB), multi-level page table walks, demand paging, page faults, and common page replacement algorithm approximations (LRU, clock). Explain how hugepages and transparent hugepages affect TLB pressure and performance; when would you enable hugepages for database workloads and what trade-offs should you consider?
MediumTechnical
60 practiced
Explain how to load, list, blacklist and unload kernel modules on a Linux system. Describe a workflow to debug a module that fails to load and logs warnings in dmesg, how to build an out-of-tree kernel module against the running kernel, and how to arrange for the module to be available across kernel updates.
HardTechnical
59 practiced
A server had an unclean shutdown and several ext4 filesystems report errors at boot. Outline a safe recovery plan: when and how to run fsck, the implications of using -y, running checks offline vs online, verifying backups before applying repairs, and options to salvage data if fsck cannot repair metadata. Also contrast procedures and risks for XFS and NTFS recovery tools.
MediumTechnical
69 practiced
You are given a Linux server where a legacy daemon exits with errno 13 (Permission denied) when attempting to write to a socket. Describe how you would use strace to trace system calls and locate the failing syscall. Include the exact strace flags you would use to follow forks, capture networking-related syscalls, and reduce noise. Also mention the equivalent tools/approach for tracing syscall-like behavior on Windows.
HardTechnical
67 practiced
You suspect a Linux host has been root-compromised. Provide an incident response plan covering immediate containment (isolate host, preserve evidence), volatile data collection (ps, netstat, mounted filesystems, memory if possible), preserving and centralizing logs, forensic analysis steps, patching and rebuilding strategy, and communication with stakeholders. Explain when rebuilding from a known-good image is preferred over remediation on the compromised host.
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