1. Which protocol is primarily responsible for establishing and managing transmission control for reliable, ordered, and error-checked delivery of a stream of octets between applications running on hosts communicating over an IP network?
A. UDP (User Datagram Protocol)
B. IP (Internet Protocol)
C. TCP (Transmission Control Protocol)
D. ICMP (Internet Control Message Protocol)
2. In the context of data transmission across a network, what is the primary function of the Data Link Layer (Layer 2) of the OSI model?
A. To handle logical addressing (IP addresses) and routing decisions.
B. To manage end-to-end communication and segmentation of data.
C. To ensure error-free transfer of data frames between adjacent network nodes.
D. To convert data into a format suitable for transmission over the physical medium.
3. Which modulation technique is commonly used in modern DSL (Digital Subscriber Line) technologies to achieve high data rates over existing copper telephone lines?
A. Frequency Shift Keying (FSK)
B. Phase Shift Keying (PSK)
C. Discrete Multi-Tone (DMT)
D. Amplitude Modulation (AM)
4. What is the main drawback of using CSMA/CD (Carrier Sense Multiple Access with Collision Detection) as the medium access control protocol?
A. It requires complex centralized control for scheduling transmissions.
B. It cannot effectively handle high network loads due to increased collision probability.
C. It is unsuitable for wireless networks due to the ‘hidden node’ problem.
D. It results in significant overhead due to mandatory handshake procedures.
5. When transmitting data over a noisy channel, if the goal is to achieve the maximum possible reliable data rate given the channel’s bandwidth (B) and Signal-to-Noise Ratio (SNR), which theorem should be applied?
A. Nyquist Theorem
B. Shannon-Hartley Theorem
C. Nyquist-Shannon Sampling Theorem
D. Nyquist Pulse Amplitude Modulation Theorem
6. Which technique involves assigning the same IP address to multiple devices on the same network segment, typically requiring the devices to use different MAC addresses, for load balancing or redundancy?
A. Proxy ARP
B. VRRP (Virtual Router Redundancy Protocol)
C. CARP (Common Address Redundancy Protocol)
D. IP Aliasing (with Layer 2 configuration)
7. In IPv6 addressing, what is the purpose of the Link-Local Address scope (FE80::/10)?
A. To provide global connectivity across the entire internet.
B. To communicate only with devices on the same physical link/subnet.
C. To enable communication within a specific site or organization.
D. To facilitate communication with multicast groups.
8. What is the primary security concern when using DHCP option 82 (Relay Agent Information Option) in enterprise networks?
A. It can expose internal IP address pools if misconfigured.
B. It might allow unauthorized devices to spoof the relay agent’s identity.
C. It is susceptible to Denial of Service (DoS) attacks targeting the DHCP server.
D. It introduces latency that violates real-time constraints.
9. If a user attempts to access a website but the connection times out repeatedly, yet pings to the server’s IP address succeed, which layer issue is most likely responsible?
A. Layer 2 (Data Link) addressing failure.
B. Layer 3 (Network) routing issue.
C. Layer 4 (Transport) port or service failure.
D. Layer 1 (Physical) medium degradation.
10. Which error detection mechanism is generally considered more robust for detecting burst errors in long-distance data transmission compared to a simple Cyclic Redundancy Check (CRC)?
A. Parity Check
B. Checksum Calculation
C. Forward Error Correction (FEC) codes like Reed-Solomon
D. Hamming Code (Block Code)
11. In asynchronous serial communication, what is the purpose of the ‘start bit’ and ‘stop bit’?
A. To synchronize the bit timing between the transmitter and receiver.
B. To indicate the start and end of a data frame and signal character boundaries.
C. To reserve bandwidth for flow control signaling.
D. To provide error checking for the transmitted data.
12. What is the primary advantage of using MPLS (Multiprotocol Label Switching) over traditional IP routing in high-performance core networks?
A. It provides inherent end-to-end encryption capabilities.
B. It allows for simpler Quality of Service (QoS) implementation based on fixed-length labels.
C. It eliminates the need for Layer 3 addresses altogether.
D. It only supports Layer 2 traffic types, ensuring backward compatibility.
13. When analyzing the throughput of a sliding window protocol, if the propagation delay (Tp) is significantly larger than the transmission time (Tt), which window size strategy maximizes throughput?
A. Window size = 1 (Stop-and-Wait)
B. Window size = 2 * (Tt / Tp) + 1
C. Window size = Maximum integer value supported by sequence numbers
D. Window size = 2 * (Tp / Tt) + 1
14. What is the role of the Neighbor Discovery Protocol (NDP) in IPv6 networks?
A. To translate hostnames into IPv6 addresses using DNS.
B. To replace ARP, ICMP Router Discovery, and Redirect functions from IPv4.
C. To manage dynamic address assignment similar to DHCPv6 server functions.
D. To establish secure tunnels between adjacent routers.
15. In a typical data center environment utilizing Software-Defined Networking (SDN), what is the primary role of the Control Plane, as separated from the Data Plane?
A. To forward the actual data packets based on flow tables.
B. To manage the physical hardware and link status reporting.
C. To calculate and program the forwarding rules (e.g., flow tables) onto the switches.
D. To handle user authentication and access control lists.
16. Which concept describes the practice of using multiple IP addresses associated with the same MAC address on a single network interface for redundancy or load distribution, commonly seen in cluster environments?
A. MAC Address Spoofing
B. ARP Broadcasting
C. IP Aliasing
D. Secondary IP assignment
17. What characteristic of UDP makes it suitable for real-time applications like VoIP or online gaming, despite lacking guaranteed delivery?
A. Mandatory congestion control mechanisms.
B. Lower protocol overhead and minimal latency introduced by acknowledgment traffic.
C. Guaranteed in-order packet delivery.
D. Built-in data encryption features.
18. In modern data link technologies, what is the primary function of the preamble field in an Ethernet frame?
A. To specify the destination MAC address.
B. To synchronize the receiver’s clock with the incoming bit stream.
C. To indicate the start of the frame’s payload data.
D. To define the frame’s encapsulation protocol type.
19. Which networking concept is most closely associated with the challenge of preventing a large broadcast domain from overwhelming end devices with unnecessary traffic?
A. Network Address Translation (NAT)
B. VLAN implementation
C. Spanning Tree Protocol (STP)
D. Ethernet collision detection
20. What is the primary goal of using Forward Error Correction (FEC) in high-speed wireless data transmission?
A. To reduce the required transmission power.
B. To enable the receiver to recover from errors without retransmission requests.
C. To compress the data payload before transmission.
D. To strictly enforce Quality of Service guarantees.
21. In the context of network performance metrics, what does ‘Jitter’ specifically measure?
A. The total time taken for a packet to travel from source to destination.
B. The variation in delay for successive packets in a stream.
C. The percentage of data packets that are lost during transmission.
D. The maximum achievable data transfer rate under ideal conditions.
22. Which service provided by the TCP protocol ensures that data sent by the sender is received completely and without duplication or corruption at the receiver?
A. Flow Control
B. Connection Establishment (Three-way Handshake)
C. Reliable Data Transfer (using sequence numbers and ACKs)
D. Congestion Control
23. What is the primary function of the Address Resolution Protocol (ARP) in an IPv4 local area network?
A. To map IP addresses to physical MAC addresses for local frame delivery.
B. To dynamically assign IP addresses to network hosts.
C. To translate hostnames to IP addresses.
D. To determine the best path for routing traffic between subnets.
24. Consider a network where the primary constraint is the physical distance between devices, leading to long propagation times. Which factor is most sensitive to this distance?
A. Bit Error Rate (BER)
B. Propagation Delay
C. Bandwidth Utilization
D. Data Rate (bits/second)
25. Which mechanism allows a router to reduce the size of a broadcast domain by selectively forwarding or blocking broadcast traffic based on logical groupings?
A. Bridging
B. Subnetting
C. Router Interface Configuration
D. Virtual LANs (VLANs)
26. What is the fundamental difference between an unshielded twisted-pair (UTP) cable and a shielded twisted-pair (STP) cable concerning electromagnetic interference (EMI)?
A. UTP offers higher bandwidth capability than STP.
B. STP includes a metallic shield to reduce external EMI.
C. UTP is primarily used for backbone connections, while STP is for end devices.
D. STP requires specialized optical transceivers, unlike UTP.
27. In network monitoring, what does the term ‘RTO’ (Retransmission Timeout) in TCP usually represent?
A. The time required for the initial connection handshake.
B. The calculated time interval after which an unacknowledged segment is resent.
C. The maximum time allowed for a single TCP session to remain active.
D. The time needed to negotiate congestion window size.
28. Which component of a digital communication system is primarily responsible for converting the digital bit stream into an analog signal suitable for transmission over a physical medium like radio waves?
A. Demultiplexer
B. Modem (Modulator-Demodulator)
C. Encoder
D. Multiplexer
29. When a router receives an IP packet destined for a network it does not have a specific route for, which routing table entry does it consult as a final fallback?
A. The default gateway route (0.0.0.0/0).
B. The connected interface route.
C. The administrative distance metric.
D. The longest prefix match route.
30. What is the primary purpose of using Hashing functions (like SHA-256) in the context of ensuring data integrity during online transmission?
A. To encrypt the data payload, making it confidential.
B. To create a fixed-size, unique fingerprint of the data for verification.
C. To reorder packets that arrive out of sequence.
D. To compress the data before sending it.
31. Which transmission mode is characterized by sending data one bit at a time sequentially over a single channel?
A. Parallel transmission
B. Serial transmission
C. Simplex transmission
D. Duplex transmission
32. In synchronous serial transmission, what mechanism is primarily used to ensure that the receiver and sender maintain consistent bit timing?
A. Parity bits
B. Start and stop bits
C. Clock signal embedded in the data stream
D. Checksums
33. What is the primary function of the start bit and stop bit in asynchronous serial communication?
A. Error detection
B. Flow control
C. Frame synchronization
D. Data compression
34. Which layer of the OSI model is primarily responsible for the physical transmission of raw bits over a communication channel?
A. Data Link Layer
B. Network Layer
C. Physical Layer
D. Transport Layer
35. What term describes a communication setup where data can only flow in one direction at any given time, but both directions are possible sequentially?
A. Simplex
B. Half-duplex
C. Full-duplex
D. Multiplexed
36. When evaluating multiplexing techniques, what is the key differentiating factor between Time Division Multiplexing (TDM) and Frequency Division Multiplexing (FDM)?
A. TDM uses physical cables, while FDM uses wireless.
B. TDM divides bandwidth by time slots, FDM divides it by frequency bands.
C. TDM is inherently more secure than FDM.
D. FDM only supports digital signals, TDM supports analog.
37. What type of error detection method involves transmitting an extra bit (parity bit) set to ensure the total number of ‘1’s in the data frame is always even or always odd?
A. Cyclic Redundancy Check (CRC)
B. Checksumming
C. Parity Check
D. Hamming Code
38. In the context of modern data transmission protocols, what is the primary advantage of using Frame Relay over older technologies like X.25?
A. It offers guaranteed error correction at the Data Link Layer.
B. It operates primarily at the Network Layer (Layer 3).
C. It provides a simpler, connection-oriented service with lower overhead.
D. It eliminates the need for any error checking by relying on end-to-end TCP reliability.
39. Which modulation technique converts data into a continuous analog signal by varying the phase of the carrier wave?
A. Amplitude Shift Keying (ASK)
B. Frequency Shift Keying (FSK)
C. Phase Shift Keying (PSK)
D. Pulse Code Modulation (PCM)
40. When implementing error control, what is the difference between ‘Automatic Repeat Request (ARQ)’ and ‘Forward Error Correction (FEC)’?
A. ARQ corrects errors locally; FEC requires retransmission.
B. FEC adds redundant data for self-correction; ARQ requests retransmission upon error detection.
C. FEC is used for synchronous links; ARQ is used for asynchronous links.
D. ARQ is mandatory for all protocols; FEC is optional.
41. What is the primary role of the MAC (Media Access Control) sublayer in the Data Link Layer concerning shared media networks?
A. Routing packets between different networks.
B. Managing flow control between end hosts.
C. Controlling access to the physical medium to prevent collisions.
D. Encapsulating Layer 3 packets into frames.
42. In networking, what distinguishes ‘Virtual Circuit (VC) switching’ from ‘Datagram switching’?
A. Datagram ensures ordered delivery, while VC does not.
B. VC establishes a fixed path setup phase before data transfer; Datagram routes each packet independently.
C. VC is connectionless; Datagram is connection-oriented.
D. Datagram requires explicit connection establishment at the Network Layer.
43. Which protocol found in the Data Link Layer is commonly used for managing access in wireless LANs to avoid collisions before transmission?
A. CSMA/CD
B. CSMA/CA
C. Token Ring
D. HDLC
44. What is ‘Jitter’ in the context of real-time data transmission protocols like VoIP?
A. The total time required for the first packet to reach the destination.
B. The variation in packet arrival delay over time.
C. The rate at which packets are dropped due to congestion.
D. The maximum bandwidth utilization achieved.
45. In optical fiber transmission, what phenomenon causes signal degradation due to the spreading of the pulse shape as it travels down the fiber?
A. Attenuation
B. Dispersion
C. Reflection
D. Scattering
46. Which standard primarily defines the physical layer specifications for Ethernet networks operating at 100 Mbps over twisted-pair copper cables?
A. IEEE 802.3u (Fast Ethernet)
B. IEEE 802.11 (Wi-Fi)
C. IEEE 802.1Q (VLAN Tagging)
D. IEEE 802.3z (Gigabit Ethernet)
47. If a transmission system uses Manchester encoding, what does a transition (a change from high to low or low to high voltage) in the middle of a bit interval typically signify?
A. The presence of a synchronization clock signal.
B. The actual data bit value (e.g., ‘0’ or ‘1’).
C. The end of a data frame.
D. detected error requiring retransmission.
48. What is the concept of ‘Bit Error Rate (BER)’ used to measure in digital transmission?
A. The total number of bits successfully transmitted per second.
B. The ratio of erroneous bits received to the total number of bits sent.
C. The maximum achievable data rate under ideal conditions.
D. The latency introduced by protocol overhead.
49. Which protocol employs the ‘Sliding Window’ mechanism to provide flow control and reliable data transfer at the Data Link Layer?
A. ARP
B. TCP
C. HDLC
D. IP
50. In the context of network performance metrics, how does ‘Throughput’ fundamentally differ from ‘Bandwidth’?
A. Bandwidth is the actual measured data rate; Throughput is the theoretical capacity.
B. Bandwidth is the theoretical maximum capacity; Throughput is the actual rate of successful data transfer.
C. Throughput is measured in Hertz; Bandwidth is measured in bits per second.
D. They are synonymous terms in modern networking standards.
51. What is the main benefit of using a switched network topology over a bus topology for data transmission?
A. Lower cabling costs.
B. Reduced risk of collision and higher aggregate bandwidth.
C. Simpler installation and management.
D. Necessity of only one central repeater.
52. Which technique allows multiple, independent logical channels to operate simultaneously over a single physical communication link by modulating data onto multiple carrier frequencies?
A. Statistical Time Division Multiplexing (STDM)
B. Frequency Division Multiplexing (FDM)
C. Wavelength Division Multiplexing (WDM)
D. Asynchronous Transfer Mode (ATM)
53. What is the main purpose of using Cyclic Redundancy Check (CRC) instead of simple parity checking for error detection?
A. CRC can perform error correction, while parity cannot.
B. CRC is effective against burst errors, whereas parity is primarily effective against single-bit errors.
C. CRC requires less computational overhead than parity checks.
D. CRC is used for flow control, not error detection.
54. What component is essential in an optical fiber transmission system to convert the incoming electrical digital signal into optical pulses?
A. Photodetector
B. Repeater
C. LED or Laser Diode Transmitter
D. Multiplexer
55. If a data link layer protocol uses Go-Back-N ARQ, what action must the sender take upon receiving a single frame loss or error indication?
A. It sends only the single lost frame again.
B. It discards all subsequent frames already sent and retransmits the lost frame and all frames that followed it.
C. It waits for a timeout before retransmitting.
D. It sends an immediate positive acknowledgment (ACK) for the next expected frame.
56. What distinguishes ‘Baseband’ digital transmission from ‘Broadband’ transmission regarding signal utilization?
A. Baseband uses FDM; Broadband uses TDM.
B. Baseband transmits only one digital signal at a time using the entire channel bandwidth; Broadband modulates multiple signals onto different frequencies simultaneously.
C. Baseband requires optical fiber; Broadband requires twisted pair.
D. Baseband is always full-duplex; Broadband is always half-duplex.
57. Which of the following IEEE 802 standards governs the architecture and operation of Metropolitan Area Networks (MANs) that use packet-switching technology?
A. IEEE 802.11
B. IEEE 802.3
C. IEEE 802.6
D. IEEE 802.1D
58. If a digital signal needs to be transmitted over a long-distance analog line (e.g., old telephone lines), what device is necessary to convert the digital signal into a suitable analog signal?
A. Multiplexer
B. Repeater
C. Modem
D. Hub
59. In asynchronous transmission, if the line is idle, it is typically held at what voltage level?
A. transition between high and low voltages.
B. The voltage level representing a binary ‘1’ (Mark state).
C. The voltage level representing a binary ‘0’ (Space state).
D. Zero voltage (ground).
60. What key characteristic differentiates a Statistical Time Division Multiplexing (STDM) system from a pure Synchronous TDM system?
A. STDM requires synchronization at the bit level, unlike Sync TDM.
B. STDM allocates time slots dynamically based on traffic demand, while Sync TDM allocates fixed slots regardless of activity.
C. Sync TDM is used for analog channels; STDM is used for digital channels.
D. STDM requires a slower transmission medium than Sync TDM.
61. Which IEEE 802.11 standard amendment introduced support for dual-band operation (2.4 GHz and 5 GHz) and improved data rates up to 54 Mbps using OFDM?
A. IEEE 802.11a
B. IEEE 802.11b
C. IEEE 802.11g
D. IEEE 802.11n
62. In the context of data transmission, what is the primary purpose of using Forward Error Correction (FEC) codes?
A. To increase the data transmission speed.
B. To allow the receiver to detect and correct errors without retransmission.
C. To compress the data stream before transmission.
D. To encrypt the data to ensure confidentiality.
63. Which modulation technique is commonly used in modern high-speed data transmission standards like Wi-Fi 6 (802.11ax) to achieve higher spectral efficiency?
A. Frequency Shift Keying (FSK)
B. Quadrature Amplitude Modulation (QAM)
C. Amplitude Shift Keying (ASK)
D. Phase Shift Keying (PSK)
64. What mechanism does TCP use to ensure reliable data delivery by managing the sequence and acknowledgment of segments?
A. Three-way Handshake
B. Sliding Window Protocol
C. Congestion Control Algorithm
D. Checksum Calculation
65. What differentiates a connection-oriented protocol like TCP from a connectionless protocol like UDP at the Network Layer perspective?
A. TCP uses IP addresses while UDP uses MAC addresses.
B. TCP establishes a logical connection (setup, transfer, termination) while UDP sends data packets without prior setup.
C. TCP is inherently slower due to its overhead for error correction, while UDP is faster due to lack of acknowledgments.
D. UDP operates only at the Application Layer, whereas TCP operates across Transport and Network layers.
66. In optical fiber communication, what phenomenon causes signal power loss due to the bending of the fiber?
A. Dispersion
B. Attenuation
C. Absorption
D. Macrobending Loss
67. What is the primary advantage of using MIMO (Multiple-Input Multiple-Output) technology in wireless communication systems?
A. It reduces interference from external sources.
B. It increases the coverage area significantly.
C. It increases spectral efficiency and link reliability by using multiple antennas at both ends.
D. It enables communication using lower frequency bands.
68. When comparing synchronous and asynchronous transmission, what is the defining characteristic of asynchronous transmission in terms of timing?
A. Timing is derived from a shared clock signal embedded in the data stream.
B. Timing is controlled by start and stop bits framing each character or byte.
C. Timing is synchronized using long preamble sequences before data transmission.
D. Timing information is transmitted at a fixed, high frequency separate from the data.
69. Which layer in the OSI model is primarily responsible for path determination and logical addressing (e.g., IP addresses) in a packet-switched network?
A. Data Link Layer
B. Network Layer
C. Transport Layer
D. Application Layer
70. In Carrier Sense Multiple Access with Collision Detection (CSMA/CD), what action is taken immediately after a node detects a collision?
A. It immediately retransmits the frame.
B. It transmits a jam signal and then waits a random backoff time before retransmitting.
C. It stops transmitting and waits for the channel to be clear before transmitting a short preamble.
D. It notifies all other stations to stop transmission immediately.
71. What is the main advantage of using Frequency Division Multiplexing (FDM) over Time Division Multiplexing (TDM) in certain contexts?
A. FDM requires less complex synchronization circuitry.
B. FDM can handle asynchronous data streams more naturally.
C. FDM allows for inherently higher bandwidth efficiency.
D. FDM eliminates the need for guard bands between channels.
72. Which concept in wireless communication mitigates the effects of fading by using multiple paths to receive the same signal?
A. Frequency Hopping Spread Spectrum (FHSS)
B. Orthogonal Frequency-Division Multiplexing (OFDM)
C. Diversity Techniques
D. Code Division Multiple Access (CDMA)
73. In TCP, what is the role of the ‘Congestion Window’ (cwnd)?
A. It limits the amount of data the receiver is willing to accept.
B. It limits the amount of data the sender can transmit before receiving an ACK, based on network congestion status.
C. It determines the maximum segment size (MSS) for the connection.
D. It tracks the number of retransmissions required.
74. What is the fundamental difference between a Layer 2 switch and a Layer 3 switch regarding packet forwarding decisions?
A. Layer 2 switches use IP addresses; Layer 3 switches use MAC addresses.
B. Layer 2 switches forward based on MAC addresses within a single broadcast domain; Layer 3 switches forward based on IP addresses across different networks.
C. Layer 2 switches only support half-duplex; Layer 3 switches only support full-duplex.
D. Layer 2 switches handle framing; Layer 3 switches handle flow control.
75. In the context of Internet protocols, what is the function of the Address Resolution Protocol (ARP)?
A. To translate domain names into IP addresses.
B. To translate IP addresses into physical MAC addresses on the local network segment.
C. To establish a connection between two end-hosts using a three-way handshake.
D. To dynamically assign IP addresses to network hosts.
76. Which concept allows a single physical medium to support multiple simultaneous logical connections, crucial for modern telephony and data networks?
A. Bit stuffing
B. Multiplexing
C. Attenuation Compensation
D. Error Detection
77. What is the primary reason that Ethernet networks, by default, employ Collision Detection (CD) in older half-duplex shared media?
A. To ensure all devices receive broadcast messages.
B. To prevent frames from overflowing the buffers of destination devices.
C. To guarantee channel access priority for high-priority traffic.
D. To detect when two or more stations transmit simultaneously on the same shared medium.
78. In the context of the TCP/IP model, which layer is responsible for framing, error detection at the link level, and physical addressing (MAC addresses)?
A. Internet Layer
B. Network Access Layer (or Link Layer)
C. Host-to-Host Layer
D. Application Layer
79. If a transmission system uses spread spectrum techniques to spread its signal over a wider bandwidth than the base signal requires, what is this technique primarily designed to achieve?
A. Increasing the data rate significantly.
B. Improving immunity to interference and enabling multiple access (CDMA).
C. Reducing the required transmission power to near zero.
D. Ensuring strict timing synchronization between sender and receiver.
80. Which of the following is a characteristic of Statistical Time Division Multiplexing (STDM) that distinguishes it from Synchronous TDM?
A. STDM allocates fixed time slots to each channel regardless of whether data is present.
B. STDM requires a continuous, shared clock signal for synchronization.
C. STDM allocates time slots dynamically based on demand, improving channel utilization.
D. STDM is inherently less susceptible to transmission errors.
81. In high-speed digital communication, what does the term ‘Jitter’ primarily refer to?
A. The reduction in signal amplitude over distance.
B. The variation in the timing of data signal edges relative to a reference clock.
C. The random noise floor introduced by the transmission medium.
D. The maximum frequency deviation allowed in a modulation scheme.
82. What is the primary function of the Quality of Service (QoS) mechanism in modern packet networks?
A. To encrypt all transmitted data for security.
B. To guarantee specific bandwidth, latency, or jitter limits for critical applications.
C. To automatically assign IP addresses to all connected devices.
D. To perform Layer 2 switching operations efficiently.
83. Which type of error detection technique calculates a single binary value based on the data block, suitable only for detecting odd numbers of bit errors?
A. Cyclic Redundancy Check (CRC)
B. Parity Check
C. Checksum (Internet style)
D. Hamming Code
84. When comparing UDP and TCP, if an application prioritizes low latency and does not require guaranteed delivery (e.g., live video streaming), which protocol is preferred?
A. TCP
B. UDP
C. ICMP
D. IPSec
85. What security principle is primarily addressed by the use of digital signatures in data transmission?
A. Confidentiality
B. Availability
C. Authenticity and Non-repudiation
D. Flow Control
86. In a multi-access environment using CSMA/CA (as in Wi-Fi), what does the Distributed Coordination Function (DCF) mechanism primarily aim to achieve?
A. Guaranteed Quality of Service (QoS) for all traffic.
B. Collision detection after transmission starts.
C. fair and collision-free medium access mechanism using an implied acknowledgment.
D. Efficient bandwidth allocation across geographically dispersed clients.
87. Which standard extension allows Wi-Fi networks to operate in the 60 GHz band, offering extremely high throughput over short distances?
A. IEEE 802.11ac
B. IEEE 802.11ad (WiGig)
C. IEEE 802.11ax (Wi-Fi 6)
D. IEEE 802.11ay
88. What is the purpose of the ‘Slow Start’ phase in TCP’s congestion control algorithm?
A. To probe the network capacity slowly by increasing the congestion window by one MSS per RTT.
B. To probe the network capacity aggressively by doubling the congestion window every successful RTT until a loss occurs.
C. To reduce the congestion window exponentially after detecting a packet loss.
D. To ensure the initial sequence numbers are negotiated correctly.
89. If a transmission link experiences high attenuation, which physical layer technique is MOST likely employed to restore signal integrity over long distances?
A. Adding more coding bits (FEC).
B. Increasing the modulation order (e.g., from QPSK to 16-QAM).
C. Inserting Repeaters or Regenerators.
D. Decreasing the data transmission rate.
90. In data encoding, what benefit does Manchester encoding provide over simple unipolar NRZ signaling?
A. It allows for higher data rates.
B. It guarantees a transition in the middle of every bit period for clock recovery.
C. It requires less bandwidth for transmission.
D. It is less susceptible to signal attenuation.
91. Which layer of the TCP/IP model is responsible for routing data packets across different networks, utilizing IP addresses?
A. Transport Layer
B. Application Layer
C. Internet Layer
D. Network Access Layer
92. In the context of data transmission protocols, what is the primary function of the Sliding Window mechanism in TCP?
A. To ensure the order of packets by assigning sequence numbers.
B. To multiplex multiple data streams over a single connection.
C. To control the rate of data flow to prevent buffer overflow at the receiver.
D. To establish the initial connection handshake before data transmission begins.
93. Which of the following protocols is commonly used to map a logical IP address to a physical MAC address on a local network segment?
A. ARP (Address Resolution Protocol)
B. DNS (Domain Name System)
C. DHCP (Dynamic Host Configuration Protocol)
D. ICMP (Internet Control Message Protocol)
94. What is the main difference between UDP and TCP regarding connection establishment?
A. UDP requires a four-way handshake, whereas TCP uses a three-way handshake.
B. TCP requires a three-way handshake for connection setup, while UDP is connectionless and requires no setup.
C. UDP uses a connection-oriented approach, while TCP is connectionless.
D. TCP requires acknowledgment for every packet, while UDP does not require any acknowledgments.
95. When a web browser requests a webpage via HTTP, which port number is typically used by default for the TCP connection?
A. Port 21
B. Port 80
C. Port 25
D. Port 443
96. In fiber optic communication, what phenomenon causes signal degradation as light travels through the medium over long distances?
A. Reflection
B. Refraction
C. Attenuation
D. Dispersion
97. Which concept describes the technique where multiple data streams share a single physical communication link by interleaving small segments of each stream?
A. Circuit Switching
B. Packet Switching
C. Time Division Multiplexing (TDM)
D. Frequency Division Multiplexing (FDM)
98. What is the primary purpose of a subnet mask in IPv4 addressing?
A. To identify the physical MAC address of the host.
B. To determine the network portion versus the host portion of an IP address.
C. To assign a unique global identifier to a network interface.
D. To manage the allocation of public IP addresses globally.
99. What security mechanism is crucial for ensuring data integrity and authenticity during an HTTPS session?
A. Port Address Translation (PAT)
B. Transport Layer Security (TLS) digital signatures and hashing
C. Domain Name System Security Extensions (DNSSEC)
D. Border Gateway Protocol (BGP) route filtering
100. In a client-server model using DNS, when a client queries for an IP address, what is the role of a ‘recursive’ DNS resolver?
A. It holds the definitive record for the domain’s primary records.
B. It contacts authoritative servers on behalf of the client until the final answer is found.
C. It maintains a cache of previously resolved domain names for fast lookup.
D. It translates the domain name into the client’s local MAC address.
101. Which congestion control technique involves the sender rapidly increasing its sending window size when no acknowledgments are lost, and sharply decreasing it upon detecting packet loss?
A. Slow Start
B. Additive Increase
C. Multiplicative Decrease
D. Congestion Avoidance
102. What is the primary advantage of using Carrier Sense Multiple Access with Collision Detection (CSMA/CD) in legacy Ethernet networks?
A. It guarantees bandwidth allocation for every node.
B. It allows simultaneous transmission from multiple nodes without interference.
C. It enables nodes to detect collisions and stop transmitting to allow retransmission.
D. It establishes a virtual circuit before data transfer begins.
103. When comparing data link layer framing methods, what is the primary drawback of Character Stuffing (Byte Stuffing)?
A. It requires complex hardware implementation on the transmission medium.
B. It is only effective over synchronous links.
C. It requires modifying the data stream, leading to variable frame sizes and overhead.
D. It is susceptible to noise interfering with the flag bytes.
104. What mechanism is used in TCP to prevent data loss by requiring the receiver to send feedback confirming successful receipt of data segments?
A. Checksum Calculation
B. Sequence Numbering
C. Acknowledgment (ACK) Mechanism
D. Flow Control Window
105. In Software-Defined Networking (SDN), what is the primary role of the Control Plane as separated from the Data Plane?
A. Forwarding actual data packets based on pre-defined rules.
B. Making decisions on how traffic should be routed and managed across the network.
C. Handling physical layer signaling and media access control.
D. Providing end-user application services like web browsing.
106. When analyzing network performance, what metric best describes the total volume of data successfully delivered between two points over a given time period?
A. Latency
B. Throughput
C. Jitter
D. Hop Count
107. Which addressing scheme operates at Layer 2 (Data Link Layer) and is typically hard-coded into the network interface card (NIC)?
A. IP Address (IPv4/IPv6)
B. Port Number
C. MAC Address
D. URL
108. In the context of wireless LANs (Wi-Fi), what is the main purpose of the Distributed Coordination Function (DCF)?
A. To securely encrypt data frames between the client and the Access Point.
B. To provide a mechanism for collision avoidance in the shared wireless medium.
C. To assign dynamic IP addresses to connecting devices.
D. To enable roaming of devices between different APs.
109. What is the primary security concern when a router forwards a packet that has an IP header checksum indicating an error?
A. The router must immediately drop the packet to maintain network stability.
B. The router should attempt to correct the checksum before forwarding.
C. The router should typically discard the packet and optionally send an ICMP error message.
D. The router should continue forwarding, as checksum errors are handled only at the transport layer.
110. Which routing protocol relies on link-state advertisements (LSAs) and Dijkstra’s algorithm to build a complete topological map of the network?
A. RIP (Routing Information Protocol)
B. EIGRP (Enhanced Interior Gateway Routing Protocol)
C. OSPF (Open Shortest Path First)
D. BGP (Border Gateway Protocol)
111. What technique is utilized by NAT (Network Address Translation) to allow multiple private IP addresses to share a single public IP address for outbound connections?
A. Static NAT
B. Dynamic NAT
C. Port Address Translation (PAT) or NAT Overloading
D. IP Address Hiding
112. In the context of data encoding, what is the primary advantage of using Manchester encoding over NRZ (Non-Return-to-Zero) encoding for physical layer transmission?
A. It requires less bandwidth.
B. It guarantees synchronization without the need for a separate clock signal.
C. It has higher transmission efficiency.
D. It requires simpler hardware implementation.
113. When analyzing the impact of network topology on reliability, which topology inherently provides the highest fault tolerance against single-link failures?
A. Bus Topology
B. Star Topology
C. Ring Topology
D. Mesh Topology (Fully Connected)
114. What is the main objective of the ‘Congestion Avoidance’ phase in TCP congestion control, following the Slow Start threshold?
A. To drop the congestion window size by half immediately.
B. To increase the congestion window size linearly (one segment per RTT).
C. To stop all transmission until a new Slow Start phase begins.
D. To switch the underlying transport protocol to UDP.
115. In the context of modern high-speed Ethernet, what is the role of the Spanning Tree Protocol (STP)?
A. To encrypt traffic flowing between switches.
B. To prevent Layer 2 loops by logically blocking redundant paths.
C. To dynamically assign VLAN memberships across the network.
D. To aggregate bandwidth from multiple physical links into a single logical link.
116. When comparing IPv4 and IPv6, which addressing feature primarily addresses the exhaustion of available public addresses?
A. IPv6 uses a much larger address space (128 bits).
B. IPv6 supports stateless address auto-configuration (SLAAC).
C. IPv6 has mandatory built-in IPsec support.
D. IPv6 eliminates the need for subnet masks.
117. Which type of link layer error detection technique calculates a single numerical value based on the entire data block, which is then transmitted for verification?
A. Parity Check
B. Cyclic Redundancy Check (CRC)
C. Checksum
D. Hamming Code
118. If a network administrator configures a router interface with the command ‘shutdown’, what is the immediate operational impact?
A. The interface remains operationally up but administratively down.
B. The interface enters an administrative down state, preventing Layer 1/2 operation.
C. The interface will automatically try to negotiate a connection speed.
D. The interface will cease sending routing updates on that port.
119. What concept describes a data transmission where a single sender transmits data to multiple, specific receivers simultaneously on a local segment?
A. Unicast
B. Broadcast
C. Multicast
D. Anycast
120. Which layer in the OSI model is responsible for segmenting data from the upper layers, adding port numbers for demultiplexing, and ensuring reliable end-to-end delivery?
A. Network Layer (Layer 3)
B. Data Link Layer (Layer 2)
C. Transport Layer (Layer 4)
D. Presentation Layer (Layer 6)
121. Which modulation technique is most commonly used for high-speed data transmission over traditional telephone lines (PSTN) due to its efficiency in spectral utilization and ability to adapt to channel conditions?
A. Frequency Shift Keying (FSK)
B. Phase Shift Keying (PSK)
C. Quadrature Amplitude Modulation (QAM)
D. Amplitude Shift Keying (ASK)
122. In the context of data link layer protocols, what is the primary function of the Hamming distance in error detection and correction codes?
A. To determine the minimum number of bits that must be changed to change one codeword into another, indicating error resilience. Kết luận Lý giải: To determine the minimum number of bits that must be changed to change one codeword into another, indicating error resilience.
B. To measure the maximum achievable data rate over a noisy channel.
C. To calculate the parity check bits for a given data frame.
D. To define the synchronization sequence between sender and receiver.
123. Which protocol is essential for dynamically assigning IP addresses to devices on a local network, improving network management efficiency?
A. ARP (Address Resolution Protocol)
B. ICMP (Internet Control Message Protocol)
C. DHCP (Dynamic Host Configuration Protocol)
D. DNS (Domain Name System)
124. network link suffers from frequent bit errors due to high noise, but the required throughput is low. Which error control method is generally preferred in this scenario?
A. Automatic Repeat Request (ARQ) with Go-Back-N.
B. Forward Error Correction (FEC) with low redundancy.
C. Automatic Repeat Request (ARQ) with Selective Repeat.
D. Forward Error Correction (FEC) with high redundancy.
125. What is the key difference between ‘connection-oriented’ and ‘connectionless’ services at the Transport Layer, exemplified by TCP and UDP, respectively?
A. Connection-oriented guarantees sequence ordering and error checking, while connectionless does not provide any reliability features.
B. Connection-oriented uses a handshake mechanism to establish state before data transfer, whereas connectionless sends packets independently without prior setup or state maintenance. Kết luận Lý giải: Connection-oriented uses a handshake mechanism to establish state before data transfer, whereas connectionless sends packets independently without prior setup or state maintenance.
C. Connection-oriented is faster but less reliable than connectionless, which prioritizes reliability.
D. Connection-oriented operates at the Network Layer, while connectionless operates at the Data Link Layer.
126. Which multiplexing technique allows multiple digital signals to share a single physical medium by assigning fixed time slots to each signal?
A. Frequency Division Multiplexing (FDM)
B. Wavelength Division Multiplexing (WDM)
C. Code Division Multiplexing (CDM)
D. Time Division Multiplexing (TDM)
127. In modern Ethernet networks (IEEE 802.3), what mechanism is primarily used to prevent data collisions on shared media segments?
A. CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
B. Token Passing
C. CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance)
D. Fixed-time slot allocation
128. Why is mandatory checksum calculation often considered less robust for error detection compared to CRC (Cyclic Redundancy Check) in high-speed data links?
A. Checksums only check for single-bit errors, whereas CRC can detect burst errors up to the degree of the generator polynomial. Kết luận Lý giải: Checksums only check for single-bit errors, whereas CRC can detect burst errors up to the degree of the generator polynomial.
B. Checksums require more processing time than CRC.
C. Checksums are only used in UDP/IP, not in link layer protocols.
D. CRC calculation requires a dedicated hardware unit, while checksums can always be done in software.
129. When designing a Quality of Service (QoS) strategy for real-time video streaming, which characteristic is generally prioritized over absolute bandwidth guarantee?
A. Minimizing maximum latency variation (jitter).
B. Ensuring perfect end-to-end reliability (zero packet loss).
C. Maximizing total network throughput.
D. Guaranteeing the highest possible BER (Bit Error Rate).
130. What is the primary role of the Address Resolution Protocol (ARP) in an IPv4 network environment?
A. To translate hostnames into IP addresses.
B. To map a known IP address to its corresponding MAC address on the local link. Kết luận Lý giải: To map a known IP address to its corresponding MAC address on the local link.
C. To route packets between different subnets.
D. To manage DHCP scope reservations.
131. Consider a scenario where two data streams, Stream A (low bandwidth, high error rate) and Stream B (high bandwidth, low error rate), need reliable transmission. Which flow control/error control combination is most suitable for Stream B?
A. Stop-and-Wait ARQ with high timeout values.
B. Selective Repeat ARQ with aggressive window size. Kết luận Lý giải: Selective Repeat ARQ with aggressive window size.
C. Simple parity check only.
D. Stop-and-Wait ARQ with low timeout values.
132. In the OSI model, where do protocols like TCP and UDP reside, and what primary service do they offer to the layers above them?
A. Network Layer; providing logical addressing and routing.
B. Data Link Layer; managing access to the physical medium.
C. Transport Layer; providing end-to-end communication services. Kết luận Lý giải: Transport Layer; providing end-to-end communication services.
D. Application Layer; managing user interface interactions.
133. What is the primary consequence of having a transmission medium with a very high Signal-to-Noise Ratio (SNR) on data transmission capacity?
A. It decreases the required bandwidth due to lower error correction needs.
B. It increases the maximum theoretical data rate achievable, according to Shannon’s capacity theorem. Kết luận Lý giải: It increases the maximum theoretical data rate achievable, according to Shannon’s capacity theorem.
C. It forces the system to use mandatory simple On-Off Keying (OOK).
D. It has no direct impact, as capacity is solely determined by bandwidth.
134. Which type of switching involves establishing a dedicated physical path between two endpoints before any data transfer begins, ensuring constant throughput and low latency?
A. Packet Switching
B. Message Switching
C. Circuit Switching. Kết luận Lý giải: Circuit Switching.
D. Datagram Switching
135. When implementing a modem over analog lines, why is it generally beneficial to use differential modulation schemes (like DPSK or QAM) over simple absolute modulation (like ASK or DPSK)?
A. Differential schemes eliminate the need for carrier synchronization.
B. Differential schemes simplify the error detection process.
C. Differential schemes are inherently resistant to common transmission impairments like phase jitter and signal fading by comparing relative phase/amplitude changes. Kết luận Lý giải: Differential schemes are inherently resistant to common transmission impairments like phase jitter and signal fading by comparing relative phase/amplitude changes.
D. Differential schemes require significantly lower bandwidth.
136. What distinguishes the Selective Repeat ARQ protocol from the Go-Back-N ARQ protocol in terms of efficiency when packet loss occurs?
A. Selective Repeat only retransmits the corrupted frame, while Go-Back-N retransmits the corrupted frame and all subsequent frames in the window. Kết luận Lý giải: Selective Repeat only retransmits the corrupted frame, while Go-Back-N retransmits the corrupted frame and all subsequent frames in the window.
B. Selective Repeat requires a larger receiver window but a smaller sender window.
C. Go-Back-N is inherently faster because it does not require sequence numbers for out-of-order packets.
D. Selective Repeat mandates the use of FEC, whereas Go-Back-N does not.
137. In Synchronous Optical Networking (SONET) or SDH, what is the primary purpose of the Pointer mechanism within the SONET frame structure?
A. To indicate the payload start position relative to the frame header, accommodating network timing jitter or misalignment. Kết luận Lý giải: To indicate the payload start position relative to the frame header, accommodating network timing jitter or misalignment.
B. To specify the error detection algorithm used (e.g., CRC vs. Parity).
C. To synchronize the frame clock between the sender and receiver.
D. To prioritize traffic flows based on QoS requirements.
138. When evaluating a network channel for digital transmission, what does the Nyquist theorem primarily define in relation to bandwidth?
A. The maximum achievable data rate given a specific level of noise power.
B. The maximum number of distinct signal levels that can be reliably distinguished for a given bandwidth. Kết luận Lý giải: The maximum number of distinct signal levels that can be reliably distinguished for a given bandwidth.
C. The minimum required bandwidth to transmit a signal of a given frequency.
D. The probability of bit errors occurring per second.
139. What inherent limitation makes pure Frequency Shift Keying (FSK) generally unsuitable for extremely high-speed data transmission compared to higher-order modulation schemes?
A. FSK requires excessive channel bandwidth proportional to the data rate.
B. FSK suffers severely from phase noise and amplitude distortion.
C. FSK efficiency (bits/Hz) is inherently low as it requires distinct, separated frequencies for each bit or symbol. Kết luận Lý giải: FSK efficiency (bits/Hz) is inherently low as it requires distinct, separated frequencies for each bit or symbol.
D. FSK requires complex error correction coding.
140. In the context of network routing, what is the main advantage of using a Link State routing protocol (like OSPF) over a Distance Vector protocol (like RIP)?
A. Link State protocols require less computational power on each router.
B. Link State protocols converge faster and have fewer ‘counting to infinity’ problems because routers have a complete topological map of the network. Kết luận Lý giải: Link State protocols converge faster and have fewer ‘counting to infinity’ problems because routers have a complete topological map of the network.
C. Link State protocols use simpler metric calculations based only on hop count.
D. Link State protocols are inherently more secure against routing attacks.
141. What is the primary purpose of employing a scrambling technique before modulation in high-speed digital transmission?
A. To add redundancy for error correction.
B. To ensure spectral efficiency by spreading the signal power.
C. To prevent long sequences of identical bits (like all 0s or all 1s) from causing loss of clock synchronization at the receiver. Kết luận Lý giải: To prevent long sequences of identical bits (like all 0s or all 1s) from causing loss of clock synchronization at the receiver.
D. To encrypt the data before transmission.
142. In IP-based data delivery, what role does the Time-To-Live (TTL) field serve?
A. It specifies the maximum delay permitted for packet forwarding.
B. It acts as a hop counter, ensuring that packets do not loop indefinitely in the network. Kết luận Lý giải: It acts as a hop counter, ensuring that packets do not loop indefinitely in the network.
C. It defines the priority level for network congestion handling.
D. It indicates the remaining time until the packet payload expires.
143. Which characteristic makes Asynchronous Transfer Mode (ATM) networking fundamentally different from traditional IP packet switching regarding traffic management?
A. ATM uses fixed-size cells (53 bytes) rather than variable-length packets, simplifying queuing and enabling faster hardware switching. Kết luận Lý giải: ATM uses fixed-size cells (53 bytes) rather than variable-length packets, simplifying queuing and enabling faster hardware switching.
B. ATM relies solely on CSMA/CD for medium access control.
C. ATM operates exclusively at the Physical Layer.
D. ATM does not use any form of addressing scheme.
144. What is the primary benefit of using Spread Spectrum techniques, such as Frequency Hopping Spread Spectrum (FHSS), in wireless data transmission?
A. It guarantees 100% error-free transmission.
B. It significantly increases the maximum achievable data rate.
C. It provides excellent resistance to narrowband interference and eavesdropping by spreading the signal energy over a wider frequency band. Kết luận Lý giải: It provides excellent resistance to narrowband interference and eavesdropping by spreading the signal energy over a wider frequency band.
D. It eliminates the need for power control mechanisms.
145. When an application requires guaranteed bandwidth and delay bounds, which type of Quality of Service (QoS) mechanism is typically employed at the network core?
A. Best-Effort service.
B. Integrated Services (IntServ) using Resource Reservation Protocol (RSVP). Kết luận Lý giải: Integrated Services (IntServ) using Resource Reservation Protocol (RSVP).
C. Differentiated Services (DiffServ) marking.
D. Standard FIFO queuing.
146. In a sliding window protocol, if the sender’s window size (Ws) is set equal to the receiver’s window size (Wr), what type of flow control mechanism is being used?
A. Stop-and-Wait.
B. Selective Repeat with a window size of 1.
C. Pipelined transmission (Go-Back-N or Selective Repeat). Kết luận Lý giải: Pipelined transmission (Go-Back-N or Selective Repeat).
D. Flow control based purely on buffer availability.
147. How does the process of ‘aliasing’ occur in Digital Signal Processing (DSP) during the conversion from analog to digital signals?
A. When the sampling rate is higher than twice the maximum frequency component of the analog signal. Kết luận Lý giải: When the sampling rate is higher than twice the maximum frequency component of the analog signal.
B. When the sampling rate is lower than twice the maximum frequency component of the analog signal (violating the Nyquist rate), causing high-frequency components to appear as lower frequencies. Kết luận Lý giải: When the sampling rate is lower than twice the maximum frequency component of the analog signal (violating the Nyquist rate), causing high-frequency components to appear as lower frequencies.
C. When the quantization noise exceeds the signal amplitude.
D. When the sampling process introduces phase distortion.
148. In modern high-speed fiber optic communication systems, what technique is increasingly used to increase capacity beyond traditional time or wavelength multiplexing?
A. CSMA/CD utilization.
B. Coherent detection combined with advanced Digital Signal Processing (DSP) and higher-order modulation (e.g., DP-QPSK). Kết luận Lý giải: Coherent detection combined with advanced Digital Signal Processing (DSP) and higher-order modulation (e.g., DP-QPSK).
C. Simple ASK modulation.
D. Mandatory use of Time Division Multiplexing (TDM).
149. Which concept best describes the phenomenon where data packets, traveling through a network, experience varying delays between each other, leading to degradation in real-time application quality?
A. Latency.
B. Jitter (Latency Variation). Kết luận Lý giải: Jitter (Latency Variation).
C. Throughput.
D. Protocol Overhead.
150. What is the fundamental role of the Header Check Sequence (HCS) in an ATM cell, as opposed to a standard CRC used in Ethernet frames?
A. HCS is used for encryption, while CRC is used for error detection.
B. HCS is calculated over a smaller field (only the 5-byte header) to allow for very fast, early detection of routing errors before processing the payload. Kết luận Lý giải: HCS is calculated over a smaller field (only the 5-byte header) to allow for very fast, early detection of routing errors before processing the payload.
C. HCS ensures the cell size is always 53 bytes, regardless of payload content.
D. HCS is used for flow control acknowledgments.