Network Systems PDF

1. Basic Network Concepts and Models Network Types: ○ Personal Area Network (PAN): Close-range, often Bluetooth, e.g., phone, watch. ○ Local Area Network (LAN): Small to medium area, Ethernet-based, wired/wireless connections. ○ Campus Area...

1. Basic Network Concepts and Models Network Types: ○ Personal Area Network (PAN): Close-range, often Bluetooth, e.g., phone, watch. ○ Local Area Network (LAN): Small to medium area, Ethernet-based, wired/wireless connections. ○ Campus Area Network (CAN): Covers larger areas like campuses. ○ Wide Area Network (WAN): Extensive areas, cities or countries, uses diverse technologies like SONET, Frame Relay​(CPNT217 - 1. Basic Netw…). OSI vs. TCP/IP Models: ○ OSI Model: 7 layers (Physical, Data Link, Network, Transport, Session, Presentation, Application) – each layer serves a distinct function. ○ TCP/IP Model: Simpler 4 layers (Network Access, Internet, Transport, Application); primarily used in practical applications​(CPNT217 - 1. Basic Netw…). Standards and Organizations: ○ IANA: Manages IP addresses. ○ IEEE: Sets standards for physical equipment, MAC addresses. ○ ANSI, ITU, ISO: Oversee various international and national standards​(CPNT217 - 1. Basic Netw…). 2. Physical Layer (Layer 1) Role: Manages the transmission and reception of raw bits over a physical medium. Key Concepts: ○ Simplex, Half-Duplex, Full Duplex: Defines data transmission directionality. ○ Transmission Media: Copper (Twisted Pair): Common for Ethernet; includes UTP and STP to reduce interference. Fiber Optic: Higher bandwidth, longer distances. Wireless (RF, Wi-Fi): Operates over specific frequency bands (e.g., 2.4 GHz for Wi-Fi)​(CPNT217 - 2. Physical L…). Connectors and Cables: ○ RJ-45 for Ethernet; RJ-11 for telephony. ○ Cable Categories: Cat 3 to Cat 8, varying from 10 Mbps to 40 Gbps​(CPNT217 - 2. Physical L…). 3. Data Link Layer (Layer 2) Sublayers: ○ Media Access Control (MAC): Interfaces with physical hardware. ○ Logical Link Control (LLC): Interfaces with Layer 3 for address management​(CPNT217 - 7. Data Link …).  Switching Principles: ○ Hubs vs. Switches: Hubs are simple, broadcast data to all ports; switches use MAC addresses to direct data, reducing collision. ○ Frame Structure: Includes header (MAC address) and trailer (error-checking). Protocols: ○ Ethernet, HDLC, MPLS: Used for encapsulating and transmitting data within networks. ○ Spanning Tree Protocol: Prevents loops in network topologies with redundant paths by blocking certain paths​(CPNT217 - 3. Data Link …)​(CPNT217 - 7. Data Link …). 4. Network Layer (Layer 3) Main Functions: ○ Determines the path for data using IP addresses. ○ Supports packet encapsulation, forwarding, and addressing. Protocols: ○ IPv4: 32-bit addressing; now facing exhaustion, mitigated by NAT and private IP ranges. ○ IPv6: 128-bit addressing, significantly expands address space. Subnetting and Addressing: ○ Subnet Mask: Divides IP addresses into network and host portions. ○ CIDR Notation: Efficiently manages IP address allocation (e.g., /24 for 255.255.255.0)​(CPNT217 - 6. Network La…)​(CPNT217 - 4. Network La…). 5. Transport Layer (Layer 4) Transport Protocols: ○ TCP (Transmission Control Protocol): Reliable, connection-oriented; uses 3-way handshake for establishing connections and ensures data integrity. ○ UDP (User Datagram Protocol): Unreliable, connectionless; faster, ideal for streaming where minor losses don’t matter. Ports: ○ Port Numbers: Differentiate applications/services on a host (e.g., HTTP on 80, HTTPS on 443). ○ Port Ranges: Well-Known (0–1023): Common services. Registered (1024–49151): Assigned by IANA. Dynamic/Private (49152–65535): Not assigned, can be used freely​(CPNT217 - 5. Transport …). 6. Application Layer (Layer 7) Common Protocols:  ○ HTTP/HTTPS: Web traffic, secure (HTTPS) with SSL/TLS encryption. ○ DNS (Domain Name System): Resolves human-readable domain names to IP addresses. ○ DHCP (Dynamic Host Configuration Protocol): Automatically assigns IP addresses to devices. ○ FTP/FTPS/SFTP: For file transfers, secure options use encryption​(CPNT217 - 8. Applicatio…). Architecture: ○ Client-Server: Centralized server provides resources, clients request. ○ Peer-to-Peer: Decentralized, each node acts as both client and server​(CPNT217 - 8. Applicatio…). 7. Troubleshooting Methodology Steps for Troubleshooting: ○ Identify the Problem: Gather information, replicate issues if possible. ○ Establish a Theory: Formulate potential causes and test hypotheses. ○ Test the Theory: Run tests to confirm or adjust the theory. ○ Implement Solution: If theory is confirmed, proceed with resolution. ○ Verify Functionality: Confirm system works as expected. ○ Document Findings: Essential for future reference and faster resolutions​(CPNT217 - 10. Troublesh…). 8. API and Scripting Fundamentals API Basics: ○ APIs allow communication between software components using structured requests and responses. ○ Types: REST (stateless, uses HTTP methods like GET, POST), SOAP (older, uses XML). API Security: ○ API Keys and Tokens: Control access to APIs, essential for authentication and monitoring. Automation with APIs: Used for tasks like data synchronization, automation, and integration across platforms​(CPNT217 - 9. API’s and …). This guide summarizes each layer and critical topic with added explanations for more context. Let me know if you'd like deeper insights into any specific area. Good luck with your study session!