Chapter 2 of 522% of exam

Operating Systems and System Administration

The operating system is the software layer that manages hardware and provides a platform for applications. IT support professionals must understand how operating systems organize files, run processes, control access, and how administrators manage them at scale. This chapter covers foundational OS concepts and everyday system administration tasks.

What an Operating System Does

An operating system coordinates all of a computer's resources and services. It abstracts the hardware so applications do not need to manage it directly. Major examples include Windows, macOS, Linux, Android, and iOS.

The OS manages resources
It allocates the CPU, memory, storage, and devices among running programs and provides services applications rely on.
The kernel is the core
The kernel handles memory management, process scheduling, and hardware access, operating in a privileged mode as the system's foundation.
Drivers enable hardware
Device drivers translate OS commands into instructions specific hardware understands, so devices like printers and GPUs work correctly.
Virtual memory extends RAM
The OS can use disk space as a page file or swap to supplement physical RAM, allowing more programs to run than would fit in memory alone.

Files, Directories, and Permissions

Data is organized by a file system into files and directories arranged in a hierarchy. Permissions control who can read, write, or execute each item. Understanding this structure is essential for navigating and securing a system.

File systems organize storage
NTFS, ext4, and APFS define how data is stored and retrieved, affecting features like maximum file size and permissions.
Directories form a hierarchy
Folders contain files and other folders, and a path describes an item's location within this tree.
Permissions control access
Read, write, and execute permissions assigned to owner, group, and others determine who can view, change, or run a file in Linux.
Commands navigate the file system
Commands like cd change directories and ls or dir list contents, forming the basics of command-line file management.

Processes and Performance

Programs run as processes that the operating system schedules and manages. Monitoring processes helps diagnose performance problems and stop misbehaving software. Multitasking lets many processes appear to run at once.

A process is a running program
It includes the program's code, current state, and allocated resources such as memory, and the OS manages its lifecycle.
Multitasking shares the CPU
The OS rapidly switches between processes, and multi-core CPUs run several truly in parallel, keeping the system responsive.
Task Manager shows activity
On Windows, Task Manager displays running processes and resource usage and can end unresponsive tasks; Linux uses tools like top.
High usage signals problems
A process consuming excessive CPU, memory, or disk often explains slowdowns and is a starting point for investigation.

User Accounts and Access Control

Operating systems separate users so each has their own settings and appropriate access. Limiting privileges protects the system from mistakes and malware. Administrators grant elevated rights only when necessary.

Least privilege improves security
Standard accounts cannot make system-wide changes without elevation, limiting the damage from malware or errors.
Elevation grants admin rights
Windows uses User Account Control prompts, and Linux uses sudo, to temporarily perform tasks requiring administrator or root access.
Directory services centralize identity
Active Directory groups users and computers into domains with shared authentication and policies for centralized management.
Group Policy enforces settings
In a Windows domain, Group Policy applies consistent configurations and restrictions across many users and computers at once.

Maintenance and Administration Tasks

Keeping systems healthy requires ongoing maintenance such as updates, backups, and software management. These tasks prevent problems and enable recovery when things go wrong. Automation and good practices make them manageable at scale.

Patching closes vulnerabilities
Applying OS and software updates fixes security flaws and bugs, making prompt patch management a core admin duty.
Backups enable recovery
Regular backups protect against hardware failure, malware, and mistakes; the 3-2-1 rule keeps three copies on two media with one offsite.
Package managers handle software
Tools like apt, yum, and dnf on Linux install, update, and remove software and its dependencies from repositories.
Safe mode aids troubleshooting
Booting with only essential drivers and services helps isolate whether problems come from third-party software or configuration.
Test your knowledge
Practice questions on Operating Systems and System Administration
Practice now →
← Previous
Technical Support Fundamentals and Computer Hardware
Next →
Networking Fundamentals: TCP/IP, DNS, and DHCP

Last updated: July 2026

Report