Data and Digital Communication Midterm Exam Reviewer PDF

DATA AND DIGITAL COMMUNICATION REVIEWER FOR MIDTERM EXAMINATION 1\. The Role of Protocols in Digital Communication - Protocols are essential for ensuring data is transmitted accurately and securely across networks. - They establish the rules for orderly and efficient data exchange bet...

DATA AND DIGITAL COMMUNICATION REVIEWER FOR MIDTERM EXAMINATION 1\. The Role of Protocols in Digital Communication - Protocols are essential for ensuring data is transmitted accurately and securely across networks. - They establish the rules for orderly and efficient data exchange between the sender and receiver. 2\. Communication Protocols - Definition: Sets of rules governing data transmission across communication networks. - Purpose: Facilitates a smooth exchange of information, allowing devices to communicate seamlessly. 3\. Key Roles of Communication Protocols - Data Sequencing: Detects packet loss or duplicates. - Data Routing: Finds the most efficient path for data between sender and receiver. - Data Formatting: Organizes bits within packets to include data, control, and addressing information. - Flow Control: Regulates data flow, preventing congestion and ensuring resource sharing. - Error Control: Detects and corrects errors by retransmitting erroneous message blocks. - Transmission Precedence and Order: Coordinates when nodes send or receive data, ensuring fair access to the network. - Connection Establishment and Termination: Manages the initiation and ending of communication sessions. - Data Security: Prevents unauthorized access to data during transmission. 4\. The OSI Model - Overview: Open Systems Interconnection (OSI) Model was introduced by ISO in 1984 as a theoretical framework for network communication. - Purpose: Helps standardize communication between heterogeneous systems and outlines steps for sending data from one computer to another. - Structure: Contains 7 layers, each with specific functions that contribute to data transmission. 5\. The OSI Reference Model Explained - Why Use a Reference Model? - Provides a standard for network communication, allowing interoperability across systems. - Each layer has its unique function, supporting other layers and ensuring communication compatibility. - Alternative Models: The TCP/IP model is also widely used, particularly in internet communications. 6\. The 7 Layers of the OSI Model - Application Layer (7): Interfaces with end-user applications, granting access to network resources. - Presentation Layer (6): Manages data formatting to ensure compatibility between communicating devices. - Session Layer (5): Enables ongoing sessions between applications, e.g., NetBIOS. - Transport Layer (4): Ensures reliable data delivery, performs error detection and correction (e.g., TCP). - Network Layer (3): Manages addressing and routing to move packets across networks (e.g., IP). - Data Link Layer (2): Handles data framing, error detection, and media access control (MAC). - Physical Layer (1): Deals with the physical components of the network (e.g., cables, NICs). 7\. The TCP/IP Model - Overview: TCP/IP is an alternative to OSI, typically represented by four layers, combining certain OSI layers for a simpler model. - Structure: - Application Layer: Manages user interface processes. - Transport Layer: Ensures accurate data transfer (e.g., TCP). - Internet Layer: Manages IP routing and separates higher layers from the physical network. - Network Access Layer: Integrates OSI\'s Network and Physical layers. 8\. Remembering the OSI Layers - Mnemonic: - 7 - Application --- All - 6 - Presentation --- People - 5 - Session --- Seem - 4 - Transport --- To - 3 - Network --- Need - 2 - Data Link --- Data - 1 - Physical --- Processing 1\. Protocols in Digital Communication - Communication Protocols: Define the rules for data transmission over networks, ensuring an orderly and efficient exchange between sender and receiver. - Key Roles: - Data Sequencing: Detects lost or duplicate packets. - Data Routing: Finds the most efficient path for data. - Data Formatting: Organizes data within packets, including control, addressing, etc. - Flow Control: Prevents congestion by regulating data flow. - Error Control: Detects and corrects message errors by retransmission. - Transmission Precedence: Manages when nodes transmit/receive data. - Connection Establishment/Termination: Initiates and closes connections. - Data Security: Protects against unauthorized data access. 2\. The OSI Model - Overview: - Stands for Open Systems Interconnection, a framework by ISO (1984) for standardizing communication between computers. - Purpose: Establishes standards for how data travels between systems, ensuring compatibility across diverse hardware and software. - 7-Layer Model: - Physical Layer: Defines physical media (e.g., cables, NICs) and data encoding (e.g., Ethernet, IEEE standards). - Data Link Layer: Controls data transfer between network devices with error detection (e.g., MAC, LLC). - Network Layer: Manages routing and addressing (e.g., IP addresses). - Transport Layer: Provides reliable data delivery (e.g., TCP in TCP/IP). - Session Layer: Manages sessions between applications (e.g., NetBIOS). - Presentation Layer: Formats data to ensure compatibility (e.g., encryption). - Application Layer: Interfaces with end-user applications. - Remembering the Layers: - All People Seem To Need Data Processing. - TCP/IP Model Comparison: - TCP/IP is a simpler, 4-layer model: Application, Transport, Internet, and Network Access layers. 3\. Multiplexing - Definition: Combining multiple signals for transmission over a single shared medium. - Purpose: - Efficiently shares limited bandwidth, prevents collision, and reduces transmission costs. - Types of Multiplexing: - Analog Multiplexing: - Frequency Division Multiplexing (FDM): Assigns different frequencies to each signal simultaneously. - Wavelength Division Multiplexing (WDM): Uses prisms to combine optical signals in fiber optics. - Digital Multiplexing: - Time Division Multiplexing (TDM): Divides time intervals among users. - Synchronous TDM: Fixed time slots for each device, even if idle. - Asynchronous TDM: Dynamic time allocation based on active data transmission. - Multiplexing Hardware: - Multiplexer (MUX): Combines multiple inputs into one output. - Demultiplexer (DEMUX): Separates signals at the receiving end. - Applications: - T-1, ISDN, and SONET are popular synchronous multiplexing technologies. - Protocols are sets of rules that govern how data is formatted, transmitted, and received over a network. They ensure smooth communication by defining how messages are sent and received. 1. TCP/IP (Transmission Control Protocol/Internet Protocol) 2. HTTP (Hypertext Transfer Protocol) 3. FTP (File Transfer Protocol) 4. SMTP (Simple Mail Transfer Protocol) - IP is a fundamental protocol in the Internet Protocol Suite, managing the routing and delivery of data packets across networks. - It operates at the Internet layer and can distribute packets through multiple routes, providing congestion control by dynamically choosing alternative paths. - TCP, a core protocol in the Internet Protocol Suite, is paired with IP to form TCP/IP, a commonly used internet protocol. - Functions of TCP: - Provides virtual circuits and reliable communication. - Ensures error detection, correction, and automatic repeat requests. - Manages reordering of packets at the destination, even if they arrive out of order. - HTTP is an application-layer protocol that forms the foundation of communication on the World Wide Web. - It allows the transfer of hypertext, which includes logical hyperlinks between nodes, enabling web browsing and data exchange across the internet. - FTP is a standard protocol for transferring files between hosts over a TCP-based network. - Channels in FTP: - Command Channel (Port 21): Used for sending commands and receiving responses. - Data Channel (Port 20): Used for actual data transfer. 1. Active FTP: - The client connects to port 21 on the server and specifies a client-side port for data transfer. - The server then connects from port 20 to the client's specified port for file transfer. 2. Passive FTP: - The client connects to port 21 on the server and issues a PASV command. - The server responds with a random port number, which the client then connects to for data transfer. - SMTP is a protocol for sending emails over IP networks, utilizing TCP port 25 to ensure reliable message transmission. - A web portal is a specially designed webpage that consolidates information from various sources. It may include features like email, forums, search engines, and e-commerce services, often allowing users to personalize the displayed information. - DNS is a hierarchical system that translates human-readable domain names into IP addresses. - It supports organizational structure and assigns domain names to IP resources, reducing the need for users to memorize IP addresses. - Hostname: Identifies the specific machine within a domain. - Domain Name: Identifies a group or organization within the network. - Top-Level Domain (TLD): The last segment of a domain name, such as.edu,.com,.gov, specifying the type or country origin of the organization.