Introduction to Computer Networking

No new information was provided, so the study notes are identical to the existing ones.

• Computer networking refers to interconnected computing devices that can exchange data and share resources
• These networks can range from private networks within a home to global networks like the Internet
• They are defined by a set of protocols that govern how devices communicate over the network

Network Components

• Hosts (or nodes): These are the end-devices in a network that can send or receive data (e.g., computers, smartphones, servers)
• Transmission media: This is the physical pathway that carries data between nodes (e.g., copper cables, fiber-optic cables, wireless radio waves)
• Network interfaces: These are the hardware components that allow hosts to connect to the transmission media (e.g., Ethernet cards, Wi-Fi adapters)
• Network devices: These devices facilitate the flow of data within the network (e.g., routers, switches, hubs)

Network Types

• Local Area Network (LAN): Connects devices within a limited area, such as a home, school, or office
• Wide Area Network (WAN): Covers a broad geographical area, connecting multiple LANs. The Internet is the largest WAN
• Metropolitan Area Network (MAN): Larger than a LAN but smaller than a WAN, typically covering a city or metropolitan area
• Personal Area Network (PAN): A network covering a very small area, typically a few meters, usually connecting a person's personal devices
• Wireless LAN (WLAN): A LAN that uses wireless communication to connect devices
• Virtual Private Network (VPN): Extends a private network across a public network, enabling users to send and receive data as if their devices were directly connected to the private network

Network Topologies

• Bus topology: All devices are connected to a single cable (the bus). It's simple but a break in the cable can disrupt the entire network.
• Star topology: All devices connect to a central hub or switch. It's more reliable than a bus topology; failure of one device doesn't affect the rest of the network
• Ring topology: Devices are connected in a circular fashion. Data travels in one direction. Failure of one device can disrupt the entire network.
• Mesh topology: Each device is connected to many other devices. It's highly redundant but expensive to implement.
• Tree topology: Combines features of bus and star topologies. Easy to expand but failure of the central hub can disrupt the network.
• Hybrid topology: Combines two or more different topologies

Network Protocols

• Protocols are sets of rules that govern data communication over a network and are essential for interoperability between different devices
• Transmission Control Protocol/Internet Protocol (TCP/IP): The foundation of the Internet. TCP provides reliable, ordered, and error-checked delivery of data, while IP handles addressing and routing
• Hypertext Transfer Protocol (HTTP): Used for communication between web browsers and web servers
• Hypertext Transfer Protocol Secure (HTTPS): A secure version of HTTP that uses encryption to protect data
• File Transfer Protocol (FTP): Used for transferring files between computers
• Simple Mail Transfer Protocol (SMTP): Used for sending email
• Post Office Protocol (POP) and Internet Message Access Protocol (IMAP): Used for retrieving email from a mail server
• Domain Name System (DNS): Translates domain names (e.g., google.com) to IP addresses
• Dynamic Host Configuration Protocol (DHCP): Automatically assigns IP addresses and other network configuration information to devices on a network
• Simple Network Management Protocol (SNMP): Used for monitoring and managing network devices

Network Models

• Open Systems Interconnection (OSI) model: A conceptual framework that standardizes the functions of a telecommunication or computing system into seven abstraction layers:
  • Physical layer: Handles the physical cables or wireless links, voltage, and data rates.
  • Data link layer: Provides error-free transmission of data frames between two nodes over the physical layer
  • Network layer: Handles routing of data packets between different networks. IP operates at this layer
  • Transport layer: Provides reliable or unreliable delivery of data between processes. TCP and UDP operate at this layer
  • Session layer: Manages connections between applications.
  • Presentation layer: Handles data encryption, decryption, compression, and conversion.
  • Application layer: Provides network services to applications, like HTTP, SMTP, and FTP
• TCP/IP model: A practical model with four layers:
  • Link layer: Corresponds to the physical and data link layers of the OSI model
  • Internet layer: Corresponds to the network layer of the OSI model.
  • Transport layer: Similar to the transport layer of the OSI model
  • Application layer: Combines the session, presentation, and application layers of the OSI model

Addressing

• IP address: A unique numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication
  • IPv4: Uses 32-bit addresses, represented in dotted decimal notation (e.g., 192.168.1.1). Limited address space.
  • IPv6: Uses 128-bit addresses, represented in hexadecimal notation. Vastly larger address space.
• MAC address: A unique hardware address assigned to a network interface card (NIC) by the manufacturer. Used for communication within a local network.

Routing

• Routing is the process of selecting the best path for data to travel from source to destination
• Routers are network devices that forward data packets based on their destination IP addresses
• Routing protocols:
  • Interior Gateway Protocols (IGPs): Used for routing within an autonomous system (e.g., RIP, OSPF, EIGRP).
  • Exterior Gateway Protocols (EGPs): Used for routing between autonomous systems (e.g., BGP).

Network Security

• Firewalls: Network security systems that monitor and control incoming and outgoing network traffic based on predetermined security rules.
• Intrusion Detection Systems (IDS): Monitor network traffic for malicious activity and generate alerts
• Intrusion Prevention Systems (IPS): Actively block or prevent detected intrusions
• Encryption: Converting data into a coded format to prevent unauthorized access. Examples include SSL/TLS for secure web communication and VPNs for secure remote access
• Authentication: Verifying the identity of users or devices attempting to access a network. Examples include passwords, multi-factor authentication, and digital certificates
• Access Control Lists (ACLs): Rules that specify which users or devices are allowed to access certain network resources

Network Performance

• Bandwidth: The maximum rate of data transfer across a network connection, usually measured in bits per second (bps)
• Latency: The delay in data transfer between two points on a network, usually measured in milliseconds (ms)
• Throughput: The actual rate of data transfer, which is often less than the theoretical bandwidth due to overhead, congestion, and other factors
• Packet loss: The percentage of data packets that fail to reach their destination
• Jitter: The variation in latency over time, which can affect real-time applications like voice and video conferencing.