Network Fundamentals Lecture

OSI Model

• Definition: Seven-layer model standardizing telecommunication/computing system functions
• Purpose: Understand network protocols interaction

TCP/IP Model

• Definition: Four-layer model for Internet communication
• Purpose: Simplifies network communication structure

Network Types

• LAN (Local Area Network): Connects devices in close proximity (e.g., building/campus)
• WAN (Wide Area Network): Connects multiple LANs over large geographical areas

Key Network Devices

• Router: Forwards data packets, uses IP addresses
• Switch: Filters/forwards data in a LAN based on MAC addresses
• Hub: Broadcasts data to all devices in a LAN, less intelligent than switches
• Firewall: Monitors, filters, controls network traffic based on security policies

VPN (Virtual Private Network)

• Purpose: Secure, encrypted connection over the Internet for private data transfer

Network Protocols

• DHCP: Assigns dynamic IP addresses in a network
• DNS: Translates domain names to IP addresses
• TCP (Transmission Control Protocol): Ensures reliable, connection-oriented data transmission
• UDP (User Datagram Protocol): Connectionless, fast transmission, suitable for streaming
• ARP: Maps IP addresses to MAC addresses
• SMTP: Email sending protocol
• IMAP: Email retrieval protocol, keeps emails on server
• POP3: Older email retrieval protocol, downloads emails
• HTTP: Used for web page data transfer
• HTTPS: Secure version of HTTP with encryption
• FTP: Transfers files between client and server

Important Networking Concepts

• IP Address: Unique identifier for devices on a network
• Subnet Mask: Segments IP addresses for network/host identification
• MAC Address: Unique identifier for network interfaces
• Network Topology: Physical/logical arrangement of network devices (e.g., star, ring, bus)
• Ethernet: Wired LAN technology
• Wi-Fi: Wireless networking technology
• NAT (Network Address Translation): Translates private IPs to public IPs
• Port: Virtual endpoint for network communication
• Packet: Unit of data formatted for network transmission
• Frame: Data packet specific to the data link layer
• MTU (Maximum Transmission Unit): Largest data packet size for transmission
• Ping: Tests network connectivity
• Traceroute: Tracks packet path through a network
• Proxy Server: Intermediary server for security, content filtering, and caching
• SSID (Service Set Identifier): Unique name for Wi-Fi networks
• VPN: Secure, private network over the Internet
• QoS (Quality of Service): Prioritizes data traffic
• PoE (Power over Ethernet): Transfers data and power via Ethernet cables
• VLAN (Virtual LAN): Logical group within a physical network
• SNMP (Simple Network Management Protocol): Monitors/manages network devices
• STP (Spanning Tree Protocol): Prevents loops in Ethernet networks

Cables and Connectors

• UTP (Unshielded Twisted Pair): Common network cabling
• Fiber Optic: High-speed data transmission using light
• RJ45: Standard Ethernet connector
• Crossover Cable: Connects similar devices directly
• Straight-through Cable: Connects different devices
• Rollover Cable: Connects to router/switch console port
• Patch Cable: Short cable for device connection

Network Operations

• Bandwidth: Maximum data transfer rate
• Latency: Time for a packet to travel
• Jitter: Variation in latency
• Load Balancer: Distributes network traffic across servers
• Redundancy: Duplication for reliability
• Failover: Automatic switch to backup system
• Patch Panel: Manages network cables
• Rack: Houses network equipment
• Backbone: Main data-carrying network line
• Node: Any network-connected device
• Peer-to-Peer: Decentralized network model
• Client-Server: Clients request services from servers
• Multicast: Data to specific group
• Unicast: Data to single device
• Broadcast: Data to all network devices
• Circuit Switching: Dedicated communication path
• Packet Switching: Data in packets over shared network

Network Security

• WEP: Early, insecure Wi-Fi encryption
• WPA/WPA2/WPA3: Successive, more secure Wi-Fi encryption methods

Additional Concepts

• Baseband: Single signal bandwidth usage
• Broadband: Multiple signals sharing bandwidth
• Network Protocol: Rules for device communication
• Subnetting: Dividing IP networks
• CIDR: Allocates IP addresses, routes packets
• IPv4 & IPv6: Internet Protocol versions
• APIPA: Automatic IP assignment in absence of DHCP
• Loopback Address: Testing IP (e.g., 127.0.0.1)
• Private/Public IP Address: Internal vs. global unique IPs
• Static/Dynamic IP Address: Manually assigned vs. DHCP assigned
• Domain/TLD: Internet subset and top-level domain
• URL: Address for Internet resources