Introduction To Data Communications Flashcards
Q: What are the five components of data communication?
A:
Message: The information to be communicated (text, numbers, images, audio, video). Sender: The device that sends the message (e.g., computer, phone). Receiver: The device that receives the message (e.g., computer, TV). Transmission Medium: The physical path for data transmission (e.g., cables, radio waves). Protocol: Rules that govern data exchange (e.g., HTTP, TCP/IP).
Q: What are the four characteristics of an effective data communication system?
A:
Delivery: Data must reach the intended recipient only. Accuracy: Data must arrive without alteration. Timeliness: Data must be delivered on time (real-time for audio/video). Jitter: Minimal variation in packet arrival time.
Q: What are the modes of data flow in communication systems?
A:
Simplex: One-way communication (e.g., keyboard to monitor). Half-Duplex: Two-way communication, but only one direction at a time (e.g., walkie-talkies). Full-Duplex: Two-way simultaneous communication (e.g., phone calls).
Q: What are the key criteria for a network?
A:
Performance: Measured by throughput and delay. Reliability: Frequency of failures and recovery time. Security: Protection from unauthorized access and data loss.
Q: Describe the main network topologies.
A:
Mesh: Every device is connected to every other device. Advantages: High robustness and privacy. Disadvantages: High cost and cabling complexity. Star: Devices connect to a central hub. Advantages: Easy to install and robust. Disadvantage: Hub failure affects the entire network. Bus: All devices share a single backbone. Advantages: Simple and cost-effective. Disadvantages: Faults in the bus affect the entire network. Ring: Devices form a closed loop, passing data in one direction. Advantages: Easy to install and reconfigure. Disadvantage: Single point of failure.
Q: What are the categories of networks and their key features?
A:
LAN (Local Area Network): Small area, high speed (e.g., office networks). WAN (Wide Area Network): Covers large distances using technologies like packet switching. MAN (Metropolitan Area Network): Connects LANs within a city using high-speed backbones.
Q: What are examples of commonly used Internet protocols?
A:
HTTP: For web data transfer. TCP/IP: For reliable communication between devices. SMTP: For email exchange.
Q: What are the two types of standards in networking?
A:
De Facto: Widely used but not officially approved (e.g., TCP/IP). De Jure: Approved by a recognized body (e.g., IEEE standards).
Q: What are examples of transmission mediums in data communication?
A:
Twisted-pair wire Coaxial cable Fiber-optic cable Radio waves
Q: How is data represented in communication systems?
A:
Text: ASCII or Unicode encoding. Numbers: Binary representation. Images: Matrix of pixels. Audio: Waveform recordings. Video: Sequence of images (frames) in motion.
Q: What is jitter, and why is it significant in data communication?
A:
Definition: Variation in packet arrival time. Impact: Affects real-time applications like video streaming and VoIP. Examples: If the 2nd packet arrives 10ms earlier than expected: Clumping. If it arrives 10ms late: Dispersion.
Q: What factors influence network performance?
A:
Transit Time: Time for data to travel from sender to receiver. Response Time: Time between a request and its response. Throughput: Amount of data transmitted per unit time. Delay: Time lag caused by congestion or hardware inefficiencies.
Q: What are key measures of network reliability?
A:
Frequency of failures. Recovery time after failures. Robustness during disasters
Q: Differentiate between point-to-point and multipoint connections.
A:
Point-to-Point: Dedicated link between two devices (e.g., phone line). Multipoint: A single link shared by multiple devices, either spatially or temporally.
Q: What are the pros and cons of mesh, star, bus, and ring topologies?
A:
Mesh: Pros: High robustness, fast communication. Cons: Expensive, complex cabling. Star: Pros: Easy to install, robust. Cons: Hub failure disrupts the network. Bus: Pros: Cost-effective, simple. Cons: Cable failure stops all transmissions. Ring: Pros: Easy reconfiguration. Cons: A single break affects the network unless bypass mechanisms exist.