System Administration

Introduction to System Administration

• System administration manages and maintains computer systems, networks, and infrastructure.
• It ensures the availability, reliability, and security of IT resources.

Goals of System Administration

• System should have availability and reliability.
• Security of data and infrastructure should be maintained.
• Optimize system performance and resource utilization.
• Support users and stakeholders.
• Enable IT infrastructure scalability.

Philosophy of System Administration

• Proactive Maintenance prevents issues before they arise.
• Automation reduces manual effort and errors.
• Continuous Learning keeps one updated with new technologies.
• Collaboration involves working with developers and IT teams.
• Documentation keeps records for troubleshooting.

Challenges in System Administration

• Managing diverse and complex systems is a challenge.
• Protecting against cybersecurity threats is a challenge.
• Ensuring system scalability while maintaining performance is important.
• Balancing budget constraints and IT needs is important.
• Meeting evolving user expectations can be challenging.

Common Practices

• Monitoring tracks system performance and security.
• Backup & Recovery implements robust backup strategies.
• Patch Management regularly updates software to fix vulnerabilities.
• Configuration Management maintains system consistency.
• Incident Response establishes protocols for handling IT issues.

Computer System Components

• The CPU (Central Processing Unit) executes instructions.
• RAM (Random Access Memory) temporarily stores data for fast access.
• Storage provides permanent data storage (e.g., HDD, SSD).
• Input Devices include devices like keyboard and mouse for interaction.
• Output Devices include devices like monitors and printers for displaying output.
• The Motherboard connects and allows communication between components.

Operating System Components

• The Kernel is the core component that manages system resources.
• The File System organizes data storage.
• Device Drivers facilitate OS-hardware communication.
• User Interface provides a way for users to interact (CLI/GUI).
• Networking enables communication between computers.
• Security protects system resources and data.

Unix-like Systems

• They use a monolithic kernel and hierarchical file system with strong CLI support (Bash).
• Security is managed via permissions and access control lists.
• Examples include Linux, macOS, and FreeBSD.

Windows Systems

• They use a hybrid kernel and NTFS file system with GUI-based interaction.
• They have integrated security tools like Windows Defender and UAC.
• They're widely used in desktop and enterprise environments.

OSI Model (7 Layers)

• Physical Layer manages physical connections such as cables and voltage.
• Data Link Layer ensures reliable transmission using Ethernet or Wi-Fi.
• Network Layer handles routing using the IP protocol.
• Transport Layer ensures reliable end-to-end communication using TCP or UDP.
• Session Layer manages communication sessions between applications.
• Presentation Layer encrypts and translates data.
• Application Layer provides network services such as HTTP, FTP, and SMTP.

TCP/IP Model (4 Layers)

• Application Layer combines OSI layers 5-7, using protocols like HTTP, FTP, and DNS.
• Transport Layer provides end-to-end communication using TCP or UDP.
• Internet Layer routes packets across networks using the IP protocol.
• Link Layer deals with physical connections and data transfer using Ethernet or Wi-Fi.

Key Network Concepts

• IP Addressing is a unique identifier for network devices.
• Subnetting divides a network into smaller segments.
• Routing directs data between networks.

Network Planning Considerations

• Security involves using firewalls, encryption, and access control.
• Redundancy involves implementing backup connections to avoid downtime.
• Bandwidth Management optimizes network traffic.
• Scalability involves designing infrastructure for future expansion.