WorksheetsIntroduction to the Physical Layer
Total questions: 75
Worksheet time: 38mins
Which OSI layer is responsible for sending raw bits using physical network equipment?
Physical layer transmits raw bits through media
Data Link layer handles frames and MAC
Network layer routes packets across networks
Transport layer manages end-to-end reliability
What does the Physical layer primarily transmit between devices?
Structured frames with headers
Encrypted sessions and keys
Raw bits represented as 0s and 1s
Application-level messages
Which set best lists components associated with the Physical layer?
Cables, connectors, plugs
Sessions, presentations, codecs
Sockets, ports, processes
Routers, subnets, gateways
At the sender, the Physical layer converts data into signals for travel; what process at the receiver reverses this?
Fragmentation of packets
Multiplexing of channels
Compression to reduce size
Demodulation to recover data
Which statement best describes modulation in the context of the Physical layer?
Assigning IP addresses to hosts
Acknowledging segments for reliability
Encrypting payloads for security
Mapping bits onto carrier signals
Which media are explicitly mentioned for Physical layer signal transmission?
Optical fiber
Virtual private tunnels
Copper cables
Wireless links
Which of the following is NOT a Physical layer responsibility?
Defining hardware signal types
Controlling speed and timing
Establishing end-to-end sessions
Choosing direction of data flow
Which transmission mode involves data flowing both directions but not simultaneously?
Simplex communication only
Full-duplex simultaneous both ways
Broadcast to multiple receivers
Half-duplex alternating directions
How does the Physical layer ensure signals are properly sent and recovered?
By modulation and demodulation
By routing through optimal paths
By window-based flow control
By checksum error correction
Which pair correctly matches function to layer role at OSI Layer 1?
Encoding and decoding: Physical layer
Bit-by-bit transmission: Physical layer
Data control timing: Physical layer
Session establishment: Physical layer
In the diagram labeled “Bit-by-Bit Transmission,” what process is depicted between the physical layers across the transmission media?
Frame-by-frame delivery across layered stack
Sequential bit transfer across the medium
Parallel byte transfer using multiple lanes
Packet switching with route determination
The encoding plot shows rectangular pulses labeled 0 and 1 over time. Which statement best explains how bits are represented?
Phase rotation maps bits to symbols
Bit values are stored as packet headers
Voltage amplitude levels encode binary states
Frequency shifts indicate each bit value
From the signal transmission panel, what is a key difference between digital and analog signals?
Analog signals use discrete levels over time
Digital signals use continuous waveforms
Analog signals require packet encapsulation
Digital signals have distinct amplitude steps
The modulation section shows a message signal combined with a carrier signal to produce a frequency-modulated output. Which properties of the carrier can be altered during modulation?
Frequency of the carrier
Phase of the carrier
Amplitude of the carrier
Bit order of the payload
In frequency modulation as illustrated, how does the modulated waveform reflect the message signal?
Carrier amplitude doubles at each bit
Carrier phase remains constant only
Message waveform is directly transmitted unaltered
Carrier frequency varies with message amplitude
Which physical layer responsibility is highlighted by the text under “Signal Transmission”?
Scheduling medium access and collisions
Encrypting payloads at the source
Converting data to signals and decoding
Routing frames between network nodes
Which transmission mode allows data to flow in only one direction between two devices?
Simplex mode allows one-way flow only
Half duplex allows simultaneous two-way flow
Full duplex allows alternating two-way flow
Multipoint mode allows many simultaneous flows
In half duplex communication, how does data transmission occur between endpoints?
Both directions at the same time
Alternating directions, not simultaneous
Only from sender to receiver
Neither direction, just signaling
Full duplex links primarily improve performance by enabling what capability?
Automatic error-free delivery
Higher cable resistance tolerance
Longer physical link distances
Simultaneous bidirectional transmission
Data rate control at the physical layer ensures what condition during transmission?
Sender and receiver match the data rate
Routing paths are load balanced
Applications share equal bandwidth
Frames are encrypted end-to-end
Which IEEE standard corresponds to wired Ethernet at the physical layer?
IEEE 802.3 defines wired Ethernet
IEEE 802.11 defines wired Ethernet
IEEE 802.15.1 defines wired Ethernet
USB defines wired Ethernet signaling
Select all protocols that enable wireless communication at the physical layer.
USB Universal Serial Bus
IEEE 802.15.1 Bluetooth
IEEE 802.3 Ethernet
IEEE 802.11 Wi‑Fi
In a multipoint physical topology, what connects multiple devices?
A single shared link connects multiple devices
A single dedicated link connects two devices
Multiple dedicated links connect each pair
Wireless channels connect one device only
Which statement best distinguishes physical topology from logical topology in networking?
Physical shows IP addressing, logical shows VLAN assignments
Physical shows device roles, logical shows cable types
Physical shows protocols used, logical shows hardware models
Physical shows cable layout, logical shows data movement
In point-to-point topology, how many devices participate directly in a single link?
At least three devices in a ring path
Two or more devices through a central hub
Multiple devices sharing a common medium
Exactly two devices on one dedicated link
Which property is characteristic of point-to-point communication between two nodes?
Depends on a central switch for routing
Simplest path with high bandwidth per link
Uses shared bus with contention management
Requires broadcast to all nodes for delivery
In a full mesh with N devices, how many ports does each device require?
N × 2 ports for duplex links
N − 1 ports for remaining nodes
N/2 ports rounded upward
N ports including loopback
Why is mesh topology often considered costly compared to simpler topologies?
It needs advanced routing algorithms
It requires dedicated links and more ports
It uses proprietary connectors exclusively
It mandates wireless spectrum licensing
Select all advantages commonly associated with mesh topology.
Improved security and privacy
Robustness and easy fault diagnosis
Fast communication between nodes
Low wiring cost for large deployments
Which factor primarily makes installation and configuration difficult in mesh networks?
Requirement for satellite uplinks
Incompatibility with duplex communication
Dependence on outdated protocols
Complexity from many dedicated connections
A mesh network of 6 devices is required. How many ports per device are needed in a full mesh?
10 ports per device
6 ports per device
5 ports per device
3 ports per device
Which statement about mesh topology reliability is most accurate?
Reliability depends solely on central hub
Reliability increases only with wireless links
Reliability is high due to dedicated links
Reliability is low due to single shared bus
Choose all disadvantages of mesh topology highlighted in the material.
Difficult installation and configuration
High maintenance cost
Low fault isolation capability
High cable cost due to bulk wiring
In the transmit–receive diagram between device X and device Y, what does the layout represent?
A mesh link aggregated through gateways
A star topology through a central switch
A point-to-point link with duplex channels
A shared bus with collision domains
Which comparison between point-to-point and mesh topologies is correct?
Mesh offers redundancy; point-to-point does not
Point-to-point uses more cables than mesh
Both require N − 1 ports per device
Mesh provides low bandwidth per link
In a star topology, what component interconnects all devices and determines overall performance?
Active or simple central hub
Single shared backbone cable
Peer-to-peer mesh links
Wireless access controller
Which statement best describes cabling requirements in a star topology with N devices?
One long backbone cable for all nodes
Two cables per device to the hub
Exactly N cables connect devices to hub
Cables only between adjacent devices
A single device’s cable fails in a star network. What is the most likely outcome?
Data collisions increase for all
Entire network halts
Only that device disconnects
Hub amplifies the fault systemwide
Which is a disadvantage of the star topology?
Complete network depends on the hub
Difficult to identify faulty cables
Uses expensive specialty cabling
Cannot support active repeaters
Identify two correct properties of bus topology Ethernet MAC protocols.
Slotted ALOHA implemented
Pure ALOHA implemented
CDMA adopted widely
TDMA commonly used
Uses CSMA/CD exclusively
Which feature defines a bus topology’s connectivity model?
Devices form point-to-point meshes
Multiple hubs linked in a ring backbone
All devices share one backbone cable
Each device connects to a central hub
Why is bus topology considered non-robust?
Wireless interference dominates
Hub bottlenecks cause latency
Requires complex routing protocols
Backbone failure crashes the topology
Which cabling is commonly used in bus topologies?
Coaxial or twisted pair cables
Fiber-only distribution cables
Shielded ribbon multiwire
Short patch leads per device
Which advantage is typical of bus topology for small networks?
High scalability without limits
Centralized management improves QoS
Less cable needed and low cost
Independent links reduce faults
What performance effect occurs as more devices are added to a bus?
Latency decreases due to parallel paths
Collisions increase and throughput drops
Fault isolation improves significantly
Security strengthens per added node
Which statement compares single points of failure in star and bus topologies?
Star: hub failure stops network
Bus: backbone failure stops network
Bus: any drop cable failure crashes all
Star: cable failure halts all devices
Which security characteristic is typical of bus topology?
Access control enforced by central hub
Isolated links protect against eavesdropping
End-to-end encryption inherent in design
Lower security since data shares one cable
In a ring topology, how many direct neighbors does each device typically have?
One adjacent neighbor
Two adjacent neighbors
Three adjacent neighbors
Four adjacent neighbors
Which mechanism controls access to transmit data in ring networks?
Token passing method
Collision detection scheme
Carrier sensing method
Random backoff timer
What role does a monitor station serve in ring topology operations?
Manages and oversees the network
Encrypts frames end to end
Provides wireless connectivity
Stores routing tables centrally
Select all advantages commonly associated with ring topology.
High security by default
Low cost and easy to expand
Very few collisions
Fast data transmission
In ring topology, why are repeaters often required in large networks?
To allocate IP addresses
To prevent signal loss over distance
To convert wired links to wireless
To compress data before sending
What occurs when no device has data to send in a ring network using token passing?
The monitor halts the ring
The token keeps circulating
The token is destroyed
Devices enter sleep mode
Which is a typical disadvantage of ring topology?
Requires expensive hubs at every level
Excessive collisions under heavy load
Complex cabling for each branch
Failure of one node can stop the network
Tree topology is best described as which structural arrangement?
Circular peer-to-peer layout
Hierarchical star-like structure
Mesh of redundant paths
Linear bus with terminators
Which components commonly organize connectivity in tree topology?
Central and secondary hubs
Access points exclusively
Repeaters and bridges only
Routers and firewalls only
In tree topology, what is a critical vulnerability of the main backbone?
Backbone failure isolates one branch
Backbone failure only increases collisions
Backbone failure stops the whole network
Backbone failure slows but continues
How does data typically flow within tree topology?
Only through secondary hubs
Only clockwise around branches
Top-to-bottom or bottom-to-top
Random paths between peers
Refer to the diagram showing six devices in a ring. If Device 3 fails, what is the most likely immediate impact on communication?
Token speed automatically increases
Only Device 3 loses connectivity
Communication stops for the entire ring
Traffic reroutes through alternate paths
Which statement best describes a hybrid topology in computer networks?
Uses only a single centralized topology
Combines two or more different topologies
Connects devices without any structured design
Eliminates the need for network protocols
In a hybrid topology, why can each segment use its own protocol?
Because segments follow their underlying topology
Because protocols are identical across all networks
Because hubs automatically convert all protocols
Because protocols are irrelevant to physical layout
Which TWO benefits are most associated with hybrid topology design?
Ease of network expansion over time
Simplified device addressing schemes
Guaranteed zero points of failure
High flexibility in network layout
Which disadvantage commonly arises when implementing a hybrid topology?
Mandatory use of wireless-only connections
Limited scalability beyond small networks
Incompatibility with standard Ethernet hubs
Higher cost due to more cables and devices
A central hub failure causes the entire network to stop. This risk is primarily linked to which design characteristic?
Isolated ring with independent operation
Single critical point in the topology
Distributed control across all segments
Redundant mesh connections everywhere
Which statements reflect why choosing the right topology impacts network reliability? Select TWO.
Topologies like mesh provide alternate paths
Star and mesh can continue despite one link failing
Correct topology removes the need for backup
Reliability depends only on cable quality
How does topology selection influence network performance?
Performance is unaffected by topology choice
Protocols alone determine overall throughput
Topology only affects physical appearance
Appropriate topology streamlines communication
Which consideration best links topology design to security outcomes?
Security is independent of physical connections
Understanding connections enables better controls
Only encryption determines security posture
Topology design always exposes more attack paths
Which statement best describes simplex transmission mode?
Data flows randomly without direction
Data flows simultaneously both directions
Data flows alternately both directions
Data flows in one direction only
A walkie‑talkie conversation is an example of which transmission mode?
Simplex communication
Full‑duplex communication
Half‑duplex communication
Asynchronous communication
In half‑duplex mode, which behavior is correct?
Devices take turns transmitting
Only one device transmits ever
Both devices transmit at the same time
Devices never receive data
Which scenario illustrates full‑duplex communication?
Sensor sending one‑way telemetry
Two‑way radio with push‑to‑talk
Broadcast TV to viewers
Phone call between two users
Select all properties that define transmission media in networks.
Independent of interference levels
Chosen based on speed constraints
Determined by distance requirements
The physical or wireless path for data
Transmission media are mainly classified into which two categories?
Copper and fiber optics
Analog and digital paths
Synchronous and asynchronous
Guided and unguided media
Which statement about guided vs unguided media is accurate?
Unguided prevents long‑distance communication
Guided suffers no interference at all
Unguided requires fiber cores exclusively
Guided uses physical cables for signals
During a phone call, why is full‑duplex preferred over half‑duplex?
Reduces bandwidth to half the channel
Ensures messages broadcast one‑way
Prevents all signal interference
Allows simultaneous speaking and listening
