Data Communication and Networking Basics PDF

**[Data Communication and Networking Basics]** **[What is a Computer Network?]** A system of interconnected devices that share data and resources. Computer networks enable file sharing, communication, and internet access. **[Types of Networks]**: \- **[Personal Area Network (PAN)]**: A very sma...

**[Data Communication and Networking Basics]** **[What is a Computer Network?]** A system of interconnected devices that share data and resources. Computer networks enable file sharing, communication, and internet access. **[Types of Networks]**: \- **[Personal Area Network (PAN)]**: A very small network covering up to 10 meters. Examples include Bluetooth devices, wireless keyboards, and smartwatches. \- **[Local Area Network (LAN)]**: A network confined to a building or campus, typically used in offices, schools, and homes. Examples: Ethernet-based office networks. \- **[Metropolitan Area Network (MAN)]**: A network that spans a city. It connects multiple LANs together. Examples include citywide Wi-Fi and cable TV networks. \- **[Wide Area Network (WAN)]**: A network covering a large geographic area, often connecting multiple cities or countries. The internet is the largest example of a WAN. \- **[Internetwork]**: A network of networks. It allows different networks to communicate with each other, forming the global internet. **[Differences Between Internet, Intranet, and Extranet]** ***[Internet]***: A global public network for worldwide communication and information sharing. ***[Intranet]***: A private internal network for employees within an organization. ***[Extranet]***: A private network that allows controlled access to external parties like partners or vendors. 10\. ***[Networking Devices]*** **[Hub]**: Broadcasts data to all connected devices. **[Switch]**: Sends data to specific devices using MAC addresses. **[Router]**: Routes packets between different networks using IP addresses. **[Bridge]**: Connects two LANs. **[Access Point]**: Provides wireless connectivity. 2. **[Data Communication]** *[Key Elements of Data Communication]*: **[Message]**: The information to be sent. **[Sender]**: The device transmitting the message. **[Receiver]**: The device receiving the message. **[Transmission Medium:]** The communication path, which can be wired or wireless. **[Protocols]**: Rules that ensure proper communication, such as TCP/IP. ***[Characteristics of Effective Data Communication]*** ***[Four fundamental characteristics:]*** **[Delivery]**: Data must reach the correct recipient. For example, when you send an email, it must be delivered to the right address. **[Accuracy]**: The received data must be error-free. For example, a downloaded file should not be corrupted. **[Timeliness]**: Data should arrive without unnecessary delays, especially for real-time communication like video calls. **[Jitter]**: This is the variation in delay between packet arrivals. For example, consistent jitter is crucial for uninterrupted audio or video streaming. ***[Data Representation Techniques]*** **[Text]**: Represented as binary using ASCII or Unicode. Example: 'A' in ASCII → Binary 01000001. **[Number]**: Numeric data is converted into binary. Example: Decimal 10 → Binary 1010. **[Image]**: Stored as pixels in formats like JPEG or PNG. Example: A 2D grid of pixels with RGB color codes. **[Audio]**: Analog signals converted into digital format using Pulse Code Modulation (PCM). **Example**: Sampling an audio wave at regular intervals. **Video**: A sequence of images (frames) displayed at a specific rate (e.g., 30 FPS). 3\. ***Signal Types*** **[Analog Signals]**: Continuous waveforms used in AM/FM radio. **Example**: A sine wave. **[Digital Signals]**: Represent binary data (0s and 1s) as discrete pulses. **Example**: A square wave. Data Transmission a. ***[Digital Conversion]*** ***[For digital to analalog]*** **[Line Coding]**: Converts binary data to signals. Types: **[Unipolar]**: Only positive voltages (e.g., 0 → 0V, 1 → +V). **[Polar]**: Positive and negative voltages. **[Bipolar]**: Alternating polarities for 1s. ***[For analog to digital]*** **[PCM (Pulse Code Modulation)]**: Converts analog signals to digital using sampling, quantization, and encoding. b\. **[Transmission Modes]** **[Parallel Transmission]**: Sends multiple bits simultaneously (e.g., printer cables). **[Serial Transmission]**: Sends bits one by one (e.g., USB). **[Multiplexing]** Combines multiple signals into one. **Types**: **[FDM (Frequency Division Multiplexing)]**: Divides channels by frequency. **[TDM (Time Division Multiplexing)]**: Divides channels by time slots. **[WDM (Wavelength Division Multiplexing):]** Used in fiber optics. **[Modes of Communication]**: **[Simplex]**: Communication is one-way only, such as a keyboard sending data to a computer. **[Half-Duplex]**: Data flows in both directions but only one direction at a time, as in walkie-talkies. **Full-Duplex**: Simultaneous two-way communication, like phone calls. 3. **[Transmission Medi]**a **[Guided Media (Wired)]**: **[Twisted Pair Cable]**: Commonly used in LANs. **[Coaxial Cable]**: Used in cable TV and older networks. **[Fiber Optics]**: Provides high-speed data transfer using light. **[Unguided Media (Wireless)]**: **[Radio Waves]**: Used in Wi-Fi and long-range communication. **[Microwaves]**: Used in satellite communication. **[Infrared]**: Used in short-range communication like remote controls. 4. **[Transmission Impairments]** ***[Transmission impairments reduce the quality of communication signals]***: **[Attenuation]**: The signal weakens as it travels farther. Solution: Use amplifiers or repeaters. **[Delay Distortion]**: Signal components arrive at different times. Solution: Use equalizers. **[Noise]**: Unwanted signals interfere with the message. Types include: **[Thermal Noise]**: Caused by heat in components. **[Crosstalk]**: Interference from nearby communication lines. **[Impulse Noise]**: Sudden bursts caused by lightning or electrical faults. 5. **[Protocols and Standards]** **[Protocols]**: ***[HTTP/HTTPS]***: Used for browsing web pages. ***[SMTP]***: Used for sending emails. ***[FTP]***: Used for transferring files. ***[DNS]***: Converts domain names to IP addresses. ***[DHCP]***: It is used to automatically to assign IP addresses to devices. ***[Telnet]***: Provides remote access to devices over a network. **[Standards]**: **[De Facto:]** Unofficial but widely adopted standards like USB. **[De Jure]**: Officially approved standards, such as IEEE 802.3 for Ethernet. 6. **[Switching Techniques]** **[Circuit Switching]**: A dedicated communication path is established before transmission. **[Example]**: Telephone calls. **[Advantages]**: Reliable, low latency. **[Disadvantages]**: Inefficient resource usage. **[Packet Switching]**: Data is divided into packets, which are transmitted independently. Example: The internet. **[Advantages]**: Efficient, scalable. **[Disadvantages]**: Potential for latency and packet loss. **[Error Detection and Correction]** ***Error Detection***: **[Parity Check]**: Adds a bit to indicate even or odd parity. **[CRC (Cyclic Redundancy Check)]**: Uses polynomial division to detect errors. **[Error Correction]**: **[Backward Error Correction]**: Requests retransmission when an error is detected. **[Forward Error Correction]**: Automatically corrects errors using redundant data. **[Network Performance]** **[Bandwidth]**: Maximum data transfer rate, measured in bits per second. **[Latency]**: Delay in data transfer, measured in milliseconds. 13\. **[Security Mechanisms]** **[Firewalls]**: Block unauthorized access. **[IDS/IPS (Intrusion Detection/Prevention Systems)]**: Detect and prevent malicious activities. 14\. ***[Common Protocols and Their Ports]*** **HTTP** (80): Web browsing. **HTTPS** (443): Secure web browsing. **FTP** (21): File transfers. **SMTP** (25): Email sending. **DNS** (53): Resolves domain names to IP addresses. **DHCP** (67/68): Assigns dynamic IP addresses. 7. **[OSI and TCP/IP Models]** ***[OSI Model]***: **[Physical Layer]**: Handles hardware connections and transmission. **[Data Link Layer]**: Provides error detection and framing. **[Network Layer]**: Manages IP addressing and routing. **[Transport Layer]**: Ensures reliable data delivery. **[Session Layer]**: Manages sessions between devices. **[Presentation Layer]**: Handles data translation and encryption. **[Application Layer]**: Provides services to users (e.g., HTTP, FTP). ***[TCP/IP Model]***: **[Network Interface]**: Combines physical and data link layer functions. **[Internet]**: Handles routing and IP addressing. **[Transport]**: Ensures reliable delivery using TCP or UDP. **[Application]**: Combines OSI session, presentation, and application layers. 8. **[Computer Network Topologies]** **[Point-to-Point]**: Two devices connected directly. ***[Bus]***: All devices share a single communication line. Simple but prone to failure if the line is damaged. ***[Star]***: Devices connect to a central hub. Failure of a device does not affect others, but hub failure affects all. ***[Ring]***: Devices form a closed loop. Failure in one connection can affect the whole network. ***[Mesh]***: Every device connects to every other device. Highly reliable but expensive. ***[Hybrid]***: Combination of different topologies for specific needs.  9. **[Addressing and Subletting]** ***[IP Address Classes]*** *Class A.* **1 -- 127**. (Network 127 is reserved for loopback and internal testing) *Class B*. **128 -- 191**. *Class C*. **192 -- 223.** *Class D*. **224 -- 239**. (Reserved for multicast) *Class E*. **240 -- 255**. (Reserved for experimental, used for research) **[Private Address Space]** [Class A]. **10.0.0.0** to **10.255.255.255** [Class B]. **172.16.0.0** to **172.31.255.255** [Class C]. **192.168.0.0** to **192.168.255.255** **[Default Subnet Masks]** [Class A]*.* **255.0.0.0** *[Class B.]* **255.255.0.0** *[Class C]. **2*****55.255.255.0** **[Subnetting]**: Subnetting divides a network into smaller parts, improving efficiency and security. Subnet Mask: Defines the network and host portions of an IP address. 10. **[Basic CMD Commands for Networking]** **Ping**: Tests connectivity to a device or website. **Ipconfig**: Displays the IP address, subnet mask, and default gateway. **[Tracert]**: Traces the route packets take to a destination. **[Nslookup]**: Resolves domain names to IP addresses. **[Netstat]**: Displays active connections and network statistics. **[Arp -a]**: Displays the ARP table for IP-to-MAC address mapping. **[𝚖𝚜𝚌𝚘𝚗𝚏𝚒𝚐]**-𝚒𝚜 𝚞𝚜𝚎𝚍 𝚝𝚘 𝚌𝚘𝚗𝚏𝚒𝚐𝚞𝚛𝚎 𝚑𝚘𝚠 𝚊 𝚌𝚘𝚖𝚙𝚞𝚝𝚎𝚛 𝚜𝚝𝚊𝚛𝚝𝚜 𝚊𝚗𝚍 𝚠𝚑𝚊𝚝 𝚙𝚛𝚘𝚐𝚛𝚊𝚖𝚜 𝚊𝚗𝚍 𝚜𝚎𝚛𝚟𝚒𝚌𝚎𝚜 𝚕𝚘𝚊𝚍 𝚠𝚑𝚎𝚗 𝚆𝚒𝚗𝚍𝚘𝚠𝚜 𝚜𝚝𝚊𝚛𝚝𝚜.