Network Topologies Basics: 114 MCQs with answers

A single shared communication line

The backbone is the single shared cable that all devices connect to in a bus topology.

All devices on the backbone

The signal travels along the entire backbone and is received by all devices, but only the intended recipient processes it.

The backbone cable is shared by all devices

If the backbone cable breaks, the entire network goes down because all devices depend on that single cable.

To absorb the signal and prevent reflection

Terminators absorb the signal at the ends of the cable, preventing reflections that would corrupt communication.

The signals collide and both are corrupted

Because the medium is shared, simultaneous transmissions cause collisions that corrupt both data packets.

CSMA/CD

CSMA/CD (Carrier Sense Multiple Access with Collision Detection) is used to listen before sending and retry after collisions.

It stops, waits a random time, and retries

After a collision, devices stop transmitting, wait a random backoff time, and then retry to avoid another collision.

It increases collision probability and reduces performance

More devices mean more contention for the shared cable, leading to more collisions and reduced per-device bandwidth.

10BASE2 and 10BASE5

10BASE2 (ThinNet) and 10BASE5 (ThickNet) used coaxial cable in a physical bus topology.

It lacks fault tolerance and scalability

The single point of failure and performance degradation with many devices make bus topology unsuitable for modern networks.

Physical topology is the actual layout, logical is how data flows

Physical topology refers to the physical cabling layout, while logical topology describes how data travels through the network.

True

This is a fundamental characteristic of bus topology: broadcast delivery with selective processing.

False

Adding devices increases collisions and reduces available bandwidth, degrading performance.

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It is the central medium through which all data travels.

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This is broadcast delivery with selective processing.

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This lack of fault tolerance is a key weakness.

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It is the protocol used to manage collisions in shared media.

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Each device checks the destination address and only accepts matching packets.

The arrangement of nodes and connections in a network

Network topology is defined as the arrangement of nodes and connections, which determines how devices are linked and data flows.

Bus

Bus topology connects all devices to a single communication line, which is its defining characteristic.

All connected devices lose connectivity

The central hub is a single point of failure; if it fails, all devices connected to it lose connectivity.

Mesh

Mesh topology offers multiple paths between devices, so if one link fails, another can be used, providing high redundancy.

It is expensive due to many cables and ports

Mesh topology requires many cables and network interfaces, making it the most expensive to implement.

Tree

Tree topology is a hybrid that connects multiple star networks to a central bus or backbone.

Logical topology differing from physical topology

Logical topology can differ from physical topology; a star-wired ring is a classic example.

A single cable break can bring down the entire network

Bus topology is vulnerable because a break in the main cable disables the whole network, making it unreliable.

Mesh

Mesh topology provides high redundancy, making it suitable for environments where downtime is unacceptable.

The entire network is disrupted

Without redundancy, a break in the ring disrupts the entire network because data can no longer complete the loop.

Star

Star topology is easy to manage and isolate faults; if a device fails, others are unaffected, but the central hub is a single point of failure.

Star is cheaper but has a single point of failure; mesh is more reliable but expensive

Star is cost-effective and easy to manage but depends on a central hub; mesh offers high reliability but at a higher cost.

False

They can differ; for example, a star-wired network can operate logically as a ring.

True

Mesh topology provides multiple paths, so a failed link does not isolate devices.

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This is the fundamental definition.

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Physical is what you see; logical is how data travels.

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These are the standard topologies.

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If the hub fails, all connected devices lose connectivity.

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This vulnerability makes it unreliable.

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If one link fails, another can be used.

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Full mesh requires a connection between every pair of devices.

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It follows a circular path.

The actual cabling and hardware connections

Physical topology is the tangible layout of cables and hardware, while logical topology is about data flow.

Bus

Bus, star, ring, and mesh are common physical topologies. VLAN, protocol, and collision domain are not physical topologies.

ring

Token ring uses a physical star (with a MAU) but the token passes in a logical ring.

The protocols and network behavior

Logical topology is defined by protocols and how data flows, not by the physical wiring.

bus

All devices share the same channel and use CSMA/CD, so it behaves like a logical bus.

All devices can see all traffic

In a logical bus, all devices share the medium and can see all traffic, which is a security risk.

It affects collision domains and broadcast domains

Logical topology defines how data flows, which affects collision and broadcast domains, and thus performance.

Logical topology is a separate concept from VLANs

Logical topology refers to data paths, while VLANs are a layer-2 segmentation technique; they are not the same.

Star

With a switch, each device has a dedicated path, so the logical topology is a star (data flows directly to the destination).

Because failures can occur in either the physical or logical layer independently

A cable break (physical) may not affect a redundant logical path, while a routing loop (logical) can cause problems even with all cables intact.

False

They can differ, as seen in Ethernet hubs (physical star, logical bus) and token ring (physical star, logical ring).

False

Logical topology refers to data paths, while VLANs are a separate layer-2 segmentation technique.

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This is the core distinction.

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These are the standard physical layouts.

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Protocols dictate how data flows.

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Without termination, signals bounce back and interfere with new transmissions.

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Because the medium is shared, simultaneous transmissions cause collisions.

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This reduces the chance of repeated collisions.

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More devices mean more contention for the shared medium.

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This misconception overlooks the broadcast nature of the shared medium.

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If the backbone breaks, all devices lose connectivity.

The signal travels in both directions and is received by all devices, but only Device C processes it.

In bus topology, the signal propagates along the backbone in both directions, reaching every device. Each device checks the destination address; only the matching device (Device C) accepts and processes the data, while others discard it. This is a broadcast delivery, not a point-to-point transmission.

Because all devices share the same cable, increasing collision probability and reducing bandwidth per device.

In a bus network, all devices share a single communication line. As more devices are added, the chance of simultaneous transmissions (collisions) increases, and the available bandwidth is divided among more devices. This scalability limitation is a key reason bus topology is unsuitable for large networks.

The terminators are missing or faulty at the ends of the backbone.

Signal reflections occur when the ends of the backbone are not properly terminated. Terminators absorb the signal; without them, signals bounce back and forth along the cable, causing reflections that corrupt communication. While too many devices can cause collisions, reflections are specifically due to missing/faulty…

It detects collisions and triggers a retransmission after a random backoff time.

CSMA/CD (Carrier Sense Multiple Access with Collision Detection) works by having devices listen before transmitting. If a collision is detected, all devices stop, wait a random amount of time, and then retry. This mechanism manages collisions but becomes inefficient as more devices are added.

In bus topology, a break in the backbone disconnects all devices; in star, a break in a link only affects that device.

The single point of failure in bus topology is the backbone cable. If it breaks, all devices on that segment lose connectivity. In contrast, a star topology uses a central hub/switch; a failure in a link to one device only affects that device, not the entire network, offering better fault tolerance.

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It scales well but inherits weaknesses of both star and bus.

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This is a classic example.

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It is a single point of failure.

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Designers must balance these factors.

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All traffic passes through the hub.

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Critical infrastructure cannot afford downtime.

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Wireless networks still have a topology based on logical connections.

Star topology, because it is easy to manage but the central hub is a single point of failure.

The star topology is easy to manage and isolate faults, but the central hub is a single point of failure. Mesh provides redundancy but is not as easy to manage and is expensive. Ring and bus have different trade-offs, but the question specifically asks for easy management and fault isolation, which star provides.

Physical: star, Logical: ring

The physical topology is star because all devices connect to a central switch. The logical topology is ring because data flows in a circular order via token passing. This is a classic example of physical and logical topologies differing.

Mesh topology, because it offers high redundancy, but it is expensive and requires many cables.

Mesh topology provides high redundancy and reliability because multiple paths exist between devices, making it suitable for data centers. The main drawback is the high cost and complexity due to extensive cabling and network interfaces.

The data is broadcast to all devices, but only the intended recipient processes it.

In a bus topology, all devices share a single communication line. Data sent by one device travels along the line and is seen by every other device, but only the intended recipient processes it. This is how bus topology works.

It scales well by connecting star networks to a backbone, but inherits weaknesses of both star and bus.

Tree topology is a hybrid where star networks are connected to a central bus or backbone. It scales well, but it inherits weaknesses from both star (central hub failure) and bus (backbone failure). This is a key trade-off.

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These are classic examples.

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Data visibility is a security concern.

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Performance is tied to how data flows.

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It enables the physical/logical difference.

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This is how the hub operates.

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Protocols are the key factor.

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Switches create point-to-point logical connections.

Logical bus, because all devices share the same communication channel and use CSMA/CD.

In early Ethernet with a hub, the physical topology is a star, but the logical topology is a bus because all devices share the same channel and use CSMA/CD to manage access. The hub does not create a ring or mesh logically, and physical and logical topologies can differ.

Logical ring; a token passes from device to device in a circular order.

In token ring networks, even though the physical wiring is a star (using a MAU), the logical topology is a ring because the token passes from device to device in a circular order. This is a classic example of physical and logical topologies differing.

Logical bus; all devices share the same channel, so any device can capture traffic.

In a logical bus, all devices share the same communication channel and see all traffic, which is a security risk because any device can capture data. This is different from a logical ring, where data passes through each device but in a controlled order, and from a logical star, which typically provides dedicated bandwi…

Because a cable break (physical) might not affect the logical path if redundancy exists, and a logical misconfiguration can cause issues even with intact cables.

Troubleshooting requires knowing both the physical and logical paths. A physical issue like a cable break might be bypassed by redundancy, while a logical issue like a routing loop can disrupt traffic even if all cables are fine. This dual understanding is essential for effective problem-solving.

Logical star; each device has dedicated bandwidth, reducing collisions and improving performance.

In a switched Ethernet network, the logical topology is a star because each device has a dedicated connection to the switch, providing dedicated bandwidth and reducing collisions. This contrasts with a logical bus (like early Ethernet) where all devices share the same channel and suffer from collisions.

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These standards used coaxial cable in a physical bus layout.

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Modern networks prioritize fault tolerance and scalability.

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A network can have a star physical layout but behave logically like a bus.

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Terminators absorb the signal to prevent this.

The new segment was not terminated, causing signal reflections that corrupt data and increase collision detection.

In a bus topology, terminators at both ends are essential to absorb signals. If a new segment is added without proper termination, signals reflect at the open end, causing corruption and frequent collisions. While cable type, attenuation, and length are real concerns, the most immediate and likely cause of signal refle…

It depends on the position of Device C and the propagation delays from A and B to C.

The collision occurs when the two signals meet, which happens at the midpoint between A and B, at time $\tau/2$. However, Device C will detect the collision only when the corrupted signal (the overlapping signals) reaches it. The time for the collision to propagate to C depends on the distance from the collision point…

0.35 Mbps

The effective throughput of the backbone is $10 \text{ Mbps} \times (1 - 0.30) = 7 \text{ Mbps}$. This total capacity is shared among 20 devices, so each device can get at most $7 / 20 = 0.35 \text{ Mbps}$ on average. This calculation accounts for the shared medium and the overhead/collision losses, illustrating the sc…

The frame travels the entire length of the backbone, is absorbed by the terminators, and no device processes it. The network remains idle.

In bus topology, every device receives the signal, but only the device with the matching destination address processes it. If no device matches, all devices discard the frame. The signal continues to the ends of the cable where terminators absorb it, preventing reflections. No collision occurs because only one device t…

Star topology provides better fault tolerance because a failure in one device's cable does not affect the entire network.

The key advantage of star topology is fault tolerance: each device has its own cable to a central switch, so a cable failure affects only that device, not the whole network. In contrast, bus topology has a single backbone that, if broken, brings down the entire network. While star topology may use more cable initially,…

Tree topology, because it scales well but inherits the single point of failure of the backbone.

The scenario describes a tree topology: multiple star networks (buildings) connected to a central backbone. The tree topology scales well, but the backbone is a single point of failure, so if it breaks, the entire network goes down. The question specifically asks for a topology that interconnects stars and also address…

Physical star, logical ring

The physical layout is a star because all devices connect to a central switch. The logical topology is a ring because data flows in a circular order using a token, which is characteristic of a ring logical topology. This matches the example given in the content.

Mesh topology, because it provides multiple paths, but it is expensive due to many cables and ports.

For high reliability, mesh topology is ideal because it offers multiple paths, so if one link fails, data can be rerouted. The main drawback is the high cost due to extensive cabling and network interfaces, as stated in the content.

The data travels along the cable, and every device sees it, but only the intended recipient processes it.

In a bus topology, all devices share a single communication line. When a device sends data, it travels along the cable, and every other device sees it, but only the intended recipient processes it. This is explicitly described in the content.

It combines star networks connected to a central backbone; a weakness is that the backbone is a single point of failure.

Tree topology is a hybrid where star networks are connected to a central backbone. It scales well, but the backbone is a single point of failure, so if it fails, the entire network goes down. This matches the content's description of tree topology.

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They are distinct concepts.

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Collision domains are directly tied to logical topology.

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Broadcast domains are related to logical topology.

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Design requires both perspectives.

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This is a specific example of physical/logical mismatch.

Logical bus, because all devices share the same collision domain and use CSMA/CD to manage access.

In early Ethernet with a hub, the physical topology is a star, but the logical topology is a bus. All devices share the same communication channel (the hub repeats signals to all ports), creating a single collision domain. CSMA/CD is used to manage access, but collisions still occur when two devices transmit at the sam…

The logical topology is dynamic and depends on the routing protocol's path selection, which may not use all physical links simultaneously.

The logical topology is determined by the actual data path, which is influenced by protocols and routing decisions. In a physical mesh, the logical topology is not necessarily a mesh; it depends on which links are actively used by the routing protocol. The protocol may choose a single path (or a few paths) at any given…

Connect the new device directly to the MAU using a single cable; the MAU will automatically include it in the logical ring.

In a token ring network with a MAU, the physical star wiring is used for ease of cabling and fault tolerance. The MAU internally creates the logical ring by connecting the ports in a circular fashion. Adding a new device simply involves plugging it into an available port on the MAU; the MAU automatically incorporates i…

Each VLAN forms a separate broadcast domain, and within a VLAN, the logical topology is a star because the switch provides dedicated bandwidth.

VLANs segment a physical switch into multiple broadcast domains, isolating traffic between VLANs. Within a single VLAN, the switch operates as a logical star: each device has a dedicated point-to-point connection to the switch, providing full-duplex communication and no collisions. This is different from a logical bus…

The logical topology remains a star, but the broadcast domains are divided, reducing unnecessary broadcast traffic.

In a switched Ethernet network, the logical topology is a star because each device has a dedicated connection to the switch. VLANs do not change the physical or logical topology; they segment the network into multiple broadcast domains. This reduces the scope of broadcast traffic, improving performance by limiting unne…