Computer Networks Overview

Computer Networks

• Networks are typically confined to a single building or campus, known as a LAN.
• Networks spanning a city or larger campus are called MANs.
• A protocol translating domain names into IP addresses is DNS.
• PANs are primarily used for personal devices within a short range.
• CANs are designed for educational institutions or corporate campuses.
• SAN means System Area Network or Storage Area Network.
• WLAN stands for Wireless Local Area Network.
• VPNs provide secure connections across public networks.
• An Intranet is an organization's private network.
• An Extranet gives limited external access to an organization's network.
• Star topology connects all devices to a central hub.
• Ring topology connects devices in a circular arrangement.
• Mesh topology provides multiple paths for data transmission.
• FTP is used for file transfers.
• TFTP is a simpler file transfer protocol.
• SCP is a secure copy protocol.
• SMTP is used to send emails.
• HTTP is primarily used for web browsing.
• A SAN is a network for connecting storage devices.
• VPNs are used for secure communication over public networks.
• A LAN is typically used in buildings or campuses.
• A MAN is often used in a city or a larger campus.
• A PAN is used for personal devices.
• Internet protocol is used for logical addressing.
• ARP translates IP addresses to MAC addresses.
• ICMP is used for error reporting and network diagnostics.
• Real-time voice communication uses RTP and SIP.
• An EPN is an Enterprise Private Network.
• A Mesh topology offers multiple paths for data transfer.
• A Storage Area Network (SAN) focuses on storage devices.
• A System Area Network (SAN) is for high-performance computing.
• A protocol primarily used to retrieve emails from a server is SMTP, IMAP, or POP3.
• A Simplex transmission allows data flow in one direction only.
• Half-duplex transmission allows data flow in both directions, but only one at a time.
• Full-duplex transmission allows data flow in both directions simultaneously.
• Coaxial cables are susceptible to electromagnetic interference.
• A Repeater regenerates and amplifies network signals.
• A Bridge connects LAN segments and filters traffic.
• A Hub broadcasts data to all connected devices.
• A Network device that connects multiple networks is a Gateway.
• Circuit switching establishes a dedicated communication path.
• Packet switching divides data into packets for transmission.
• Message switching stores messages before forwarding.
• A firewall filters network traffic based on predefined rules.
• A Network Interface Card (NIC) facilitates network connectivity.
• Error detection techniques include CRC and checksum.
• Error correction techniques include Hamming Code.
• Data is broken into smaller segments using Packet switching.
• A Wireless Local Area Network (WLAN) uses wireless communication technology.
• A Home Area Network (HAN) is used for connecting devices.

Network Protocols

• TCP (Transmission Control Protocol) provides reliable, connection-oriented data transfer.
• UDP (User Datagram Protocol) is a connectionless protocol for faster data transmission.
• SMTP (Simple Mail Transfer Protocol) is used for sending emails.
• HTTP (Hypertext Transfer Protocol) is used for web browsing.
• FTP (File Transfer Protocol) facilitates file transfer.
• SSH (Secure Shell) provides secure remote access.
• POP3 (Post Office Protocol version 3) retrieves emails from a server.
• IMAP (Internet Message Access Protocol) manages emails on a server.
• ARP (Address Resolution Protocol) maps IP addresses to MAC addresses.
• ICMP (Internet Control Message Protocol) is used for diagnostics.

Network Types

• LAN (Local Area Network) is a network covering a small geographical area.
• MAN (Metropolitan Area Network) is a network covering a larger geographical area (e.g., city).
• WAN (Wide Area Network) is a network covering a large geographical area (e.g., country).
• PAN (Personal Area Network) is for connecting personal devices in a small area.
• CAN (Campus Area Network) connects multiple LANs within a campus.
• Storage Area Network (SAN) connects storage devices.
• System Area Network (SAN) is designed for high-performance computing.
• HAN (Home Area Network) connects devices in a home.

Network Topologies

• Star Topology: Devices connect to a central hub or switch.
• Bus Topology: Devices connect to a single cable.
• Ring Topology: Devices connect in a circular arrangement.
• Mesh Topology: Devices have multiple connections.
• Hybrid Topology: Combines characteristics of different topologies.

Network Devices

• Hub: Broadcasts data to all connected devices.
• Switch: Forwards data only to the intended recipient.
• Router: Routes data packets between networks.
• Bridge: Connects multiple LAN segments.
• Gateway: Connects dissimilar networks.
• Repeater: Amplifies network signals.
• Modem: Converts digital signals to analog signals (and vice-versa).

OSI Layers

• Physical Layer (Layer 1): Defines the physical characteristics of the network.
• Data Link Layer (Layer 2): Manages error detection and addressing.
• Network Layer (Layer 3): Handles logical addressing and routing.
• Transport Layer (Layer 4): Ensures reliable data delivery.
• Session Layer (Layer 5): Manages communication sessions.
• Presentation Layer (Layer 6): Handles data formatting and encryption.
• Application Layer (Layer 7): Provides network services directly to users.

Other Key Concepts

• Firewalls: Protect networks from unauthorized access.
• MAC Addresses: Unique hardware addresses for devices.
• IP Addresses: Unique logical addresses for devices on a network.
• Subnetting: Dividing a network into smaller subnetworks.
• Routing: Determining the best path for data packets.
• Network topologies: Physical layout of a network.
• Congestion: Buildup of data packets in a network.