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Network Topology Architectures

30 questions

All types30Multiple choice14Multiple select7Matching9
Question 1Question →

A network administrator is migrating a medium-sized enterprise campus from a traditional Cisco three-tier architecture (Access, Distribution, Core) to a two-tier collapsed core architecture. Which statement accurately describes the architectural shift in responsibilities resulting from this topology change?

Show answer & explanation

Answer: The core switches combine high-speed backbone switching with distribution-layer functions such as inter-VLAN routing, security policy enforcement, and QoS boundary control.

Answer

The core switches combine high-speed backbone switching with distribution-layer functions such as inter-VLAN routing, security policy enforcement, and QoS boundary control.
In a two-tier collapsed core enterprise design, the traditional distribution and core layers are merged into a single switch tier. Consequently, the collapsed core switches must handle both high-speed packet transport (core function) and policy/routing enforcement such as inter-VLAN routing, ACLs, and QoS boundaries (distribution function).

Step-by-Step Solution

1
Analyze the traditional Cisco Three-Tier hierarchy roles
Access layer provides end-node connectivity; Distribution layer provides routing, ACL policy enforcement, and VLAN aggregation; Core layer provides high-speed backbone transport.
Understanding individual tier responsibilities is necessary to evaluate topology consolidation.
2
Evaluate the effect of collapsing the distribution layer into the core layer
The physical distribution tier is eliminated, and its functional boundaries (inter-VLAN routing, filtering, security policies) are merged into the core devices.
A two-tier collapsed core design saves cost and reduces latency in smaller enterprise environments while combining distribution and core roles into a single switch tier.

Key Concept

Two-Tier Collapsed Core Topology Functions
Estimated Time:1m 30s
Question 2Question →

A network administrator is evaluating campus design options for a multi-floor office building with modest bandwidth requirements. The team decides to implement a 2-Tier Collapsed Core topology instead of a traditional 3-Tier Cisco Campus architecture. Which of the following statements accurately describe the structural and operational traits of this Collapsed Core design? (Select two.)

Select all that apply

Show answer & explanation

Answer: The core and distribution layer functions are merged onto the same physical switch platform or redundant switch pair.; It reduces hardware expenditure and management overhead while providing adequate scalability for smaller to medium-sized networks.

Answer

The correct statements are that the core and distribution layer functions are merged onto the same physical switch platform or redundant switch pair, and that the design reduces hardware expenditure and management overhead while providing adequate scalability for smaller to medium-sized networks.
A 2-Tier Collapsed Core architecture combines the functional responsibilities of the distribution layer (routing boundaries, policy enforcement, VLAN aggregation) and core layer (high-speed transport) into a single logical or physical layer. This approach lowers equipment expenditures, simplifies maintenance, and provides an efficient design for small-to-medium enterprise campuses.

Step-by-Step Solution

1
Analyze the structural definition of a 2-Tier Collapsed Core architecture.
Identify that the core and distribution layers of a traditional 3-Tier model are combined into unified hardware.
This consolidation eliminates one tier of switches to simplify network complexity for smaller deployments.
2
Evaluate the financial and operational benefits of collapsing the core and distribution layers.
Recognize that fewer physical devices result in lower capital costs and simplified management.
Smaller campus environments do not generate enough inter-building aggregate traffic to justify a standalone core layer.
3
Differentiate access layer responsibilities and STP configuration rules.
Confirm that access switches remain necessary and that PortFast must not be applied to switch-to-switch trunks.
PortFast applied to switch interconnects leads to bridging loops, while access switches provide endpoint connectivity and local security enforcement.

Key Concept

Cisco 2-Tier Collapsed Core Campus Architecture
Question 3Question →

Match each network topology architectural layer to its primary functional responsibility within an enterprise campus or data center network.

Click a left item, then click its matching right item

Items

Campus Core Layer
Campus Access Layer
Data Center Spine Layer
Data Center Leaf Layer

Matches

Show answer & explanation

Answer

Campus Core Layer matches high-speed non-blocking backbone transport. Campus Access Layer matches direct end-user endpoint connectivity and edge policy enforcement. Data Center Spine Layer matches interconnecting all leaf switches via ECMP routing without host connections. Data Center Leaf Layer matches directly connecting servers and storage while linking to every spine switch.
Each functional layer serves a distinct architectural purpose: the Campus Core provides rapid backbone transit; the Campus Access layer connects user devices and enforces edge policies; the Data Center Spine interconnects leaf switches via ECMP without host attachments; and the Data Center Leaf connects endpoints while maintaining links to every spine.

Step-by-Step Solution

1
Identify the role of the Campus Core Layer in a 3-Tier model.
Match with high-speed packet transport without CPU-intensive filtering.
The core layer must maintain maximum packet throughput across the campus core network.
2
Identify the role of the Campus Access Layer.
Match with direct connectivity and security enforcement for user endpoints.
Access switches form the network edge where workstations and IP phones plug into the network.
3
Differentiate between Spine and Leaf layers in a Clos data center topology.
Spine switches interconnect leaf switches via ECMP, while Leaf switches connect hosts and link to all spines.
Spine switches form the core interconnect fabric without host attachment, whereas leaf switches act as access nodes for servers.

Key Concept

Campus 3-Tier and Data Center Spine-Leaf Layer Responsibilities
Question 4Question →

An enterprise network architect is designing a two-tier Spine-Leaf (Clos) topology for a data center hosting high-performance containerized workloads. The design deploys 4 Spine switches and multiple Leaf switches. Each Leaf switch is configured with 48 x 25GbE downlink ports for server connections and 4 x 100GbE uplink ports, with exactly one uplink connecting to each of the 4 Spine switches. Layer 3 routing with Equal-Cost Multi-Pathing (ECMP) is configured across all spine-leaf interconnections. Which statement correctly evaluates the architectural traits and bandwidth performance of this Spine-Leaf deployment?

Show answer & explanation

Answer: The Leaf switch layer exhibits a 3:1 oversubscription ratio for East-West traffic while delivering deterministic, equal-latency forwarding across the spine fabric between any two Leaf switches.

Answer

The Leaf switch layer exhibits a 3:1 oversubscription ratio for East-West traffic while delivering deterministic, equal-latency forwarding across the spine fabric between any two Leaf switches.
The total host downlink bandwidth per Leaf switch is 48×25 Gbps=1200 Gbps48 \times 25\text{ Gbps} = 1200\text{ Gbps}, while the total fabric uplink bandwidth is 4×100 Gbps=400 Gbps4 \times 100\text{ Gbps} = 400\text{ Gbps}. Dividing downlink by uplink capacity yields an oversubscription ratio of 1200:4001200:400, which simplifies to 3:13:1. Additionally, because every Leaf switch connects directly to all 4 Spine switches in a two-tier Clos architecture, any inter-leaf traffic takes exactly 2 switch hops (Leaf →\rightarrow Spine →\rightarrow Leaf), guaranteeing consistent, deterministic latency across equal-cost paths.

Step-by-Step Solution

1
Calculate total host-facing downlink capacity per Leaf switch.
48 ports × 25 Gbps = 1200 Gbps total downlink bandwidth.
Host access capacity is determined by multiplying the number of downlink access ports by their individual link speed.
2
Calculate total fabric-facing uplink capacity per Leaf switch.
4 ports × 100 Gbps = 400 Gbps total uplink bandwidth.
Fabric uplink capacity is determined by multiplying the number of uplink connections to the spine by their link speed.
3
Determine the oversubscription ratio of the Leaf layer.
1200 Gbps : 400 Gbps = 3:1 oversubscription ratio.
Oversubscription ratio is calculated as Total Ingress (Downlink) Bandwidth divided by Total Egress (Uplink) Bandwidth.
4
Analyze path latency and forwarding behavior of the Spine-Leaf (Clos) fabric.
Every leaf-to-leaf path is exactly 2 fabric hops (Leaf A → Spine → Leaf B) using Layer 3 ECMP across all available Spine switches.
Spine-Leaf architectures guarantee consistent East-West latency because all endpoints connected to different leaf switches are separated by the exact same number of switch hops.

Key Concept

Spine-Leaf Architecture Oversubscription and ECMP Operation
Question 5Question →

A network engineer is designing a collapsed core enterprise campus topology connecting multiple access switches to a redundant pair of core switches. The design requires all redundant uplink interfaces from each access switch to forward traffic simultaneously for bandwidth optimization and load balancing, while preventing Layer 2 loops without forcing Spanning Tree Protocol (STP) to place any physical uplink into a blocking state. Which design architecture or technology satisfies these operational requirements?

Show answer & explanation

Answer: Implementation of multichassis link aggregation (such as Cisco StackWise or Virtual Switching System) across the collapsed core switches

Answer

Implementation of multichassis link aggregation (such as Cisco StackWise or Virtual Switching System) across the collapsed core switches
In a 2-Tier Collapsed Core architecture, dual core switches operating independently would trigger Spanning Tree Protocol (STP) to block one of the redundant uplinks from each access switch to prevent Layer 2 loops. By deploying multichassis technologies such as Cisco StackWise, Virtual Switching System (VSS), or StackWise Virtual, the two core switches merge into a single logical control plane. This enables access switches to configure Multi-chassis EtherChannel (MEC), allowing all redundant physical uplinks to actively forward traffic simultaneously with balanced load distribution.

Step-by-Step Solution

1
Identify topology requirements
The topology is a 2-Tier Collapsed Core model requiring redundant uplinks from access switches to dual core switches with active-active forwarding (no STP blocked ports).
Standard STP blocks redundant paths to prevent loops, reducing aggregate bandwidth if links are unaggregated.
2
Evaluate switch virtualization and aggregation mechanisms
Multichassis technology presents dual core switches as a single logical STP bridge.
Because the access switch sees only one logical upstream device, cross-chassis EtherChannel (MEC/LACP) bundles all physical links into a single logical channel.
3
Confirm operational behavior
Traffic is load balanced across all links in the EtherChannel bundle while STP views the bundle as a single loop-free connection.
This achieves full bandwidth efficiency and instantaneous hardware-based failover.

Key Concept

Collapsed Core Topology & Multichassis EtherChannel (MEC / VSS / StackWise)
Estimated Time:2m 0s
Question 6Question →

Match each network topology architecture on the left with its primary design characteristic on the right.

Click a left item, then click its matching right item

Items

Collapsed Core Architecture
Three-Tier Campus Architecture
Spine-Leaf Data Center Architecture
SOHO Network Architecture

Matches

Show answer & explanation

Answer

Collapsed Core Architecture pairs with combining core and distribution functions into a single tier. Three-Tier Campus Architecture pairs with using distinct Access, Distribution, and Core layers. Spine-Leaf Data Center Architecture pairs with providing predictable, low-latency east-west traffic flow. SOHO Network Architecture pairs with integrating routing, switching, wireless, and security into a single appliance.
Each topology architecture serves a distinct deployment scale and traffic profile. Collapsed Core simplifies management by consolidating distribution and core functions. Three-Tier provides clear boundary separation across large campuses. Spine-Leaf ensures low, uniform latency across data center workloads. SOHO designs consolidate multi-layer functions into a single physical appliance for small sites.

Step-by-Step Solution

1
Identify the structural definition of Collapsed Core architecture.
Collapsed Core merges the distribution and core layers into a single switch tier.
Smaller campus sites do not require a separate dedicated core layer, making a two-tier collapsed design more cost-effective.
2
Identify the structural definition of Three-Tier Campus architecture.
Three-Tier relies on dedicated Access, Distribution, and Core layers.
Large multi-building campus networks require modular tier separation for traffic control, policy enforcement, and scalability.
3
Identify the structural definition of Spine-Leaf Data Center architecture.
Spine-Leaf provides deterministic east-west latency with all leaf switches directly connected to all spine switches.
Modern data center applications generate significant server-to-server traffic, requiring consistent hop counts and ECMP routing.
4
Identify the structural definition of Small Office/Home Office (SOHO) network architecture.
SOHO architectures use a single multi-function wireless router appliance.
SOHO environments have very low user counts and simple connectivity demands handled by integrated consumer or small-business devices.

Key Concept

Enterprise Network Topology Architectures
Question 7Question →

A network administrator is designing a network for a medium-sized office building. To reduce hardware costs and simplify maintenance while maintaining connectivity between access layer devices and external networks, the administrator decides to combine the responsibilities of the core layer and the distribution layer into a single set of switches. Which network topology architecture is being implemented in this enterprise design?

Show answer & explanation

Answer: Collapsed core architecture

Answer

The collapsed core architecture is being implemented because it merges the distribution layer and core layer roles into a single pair of switches.
In a collapsed core network design (also known as a two-tier campus design), the distribution layer and core layer functionality are merged into a single tier of redundant switches. This provides routing, security policy enforcement, and high-speed campus backbone connectivity on the same hardware, reducing overall cost and complexity for smaller site footprints.

Step-by-Step Solution

1
Analyze the requirements described in the scenario
The design merges core and distribution layer duties into one switch tier to save cost in a medium-sized campus.
Identifying key structural consolidations helps differentiate enterprise network models.
2
Match the requirement to the standard Cisco topology definitions
A 2-tier design where core and distribution layers are combined is specifically known as a collapsed core topology.
Collapsed core models reduce tier count while retaining access layer connections.

Key Concept

Collapsed Core Topology
Question 8Question →

An enterprise network engineering team is upgrading a data center fabric to support high-density East-West microsegmentation traffic using a Spine-Leaf architecture. Which of the following statements accurately characterize the topology rules and traffic handling of a standard two-tier Spine-Leaf design? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: Every leaf switch connects to every spine switch, and spine switches do not connect directly to each other.; Traffic traveling between endpoints connected to different leaf switches experiences a consistent, predictable hop count across the fabric.

Answer

The correct statements are: 1) Every leaf switch connects to every spine switch, and spine switches do not connect directly to each other; and 2) Traffic traveling between endpoints connected to different leaf switches experiences a consistent, predictable hop count across the fabric.
In a standard two-tier Spine-Leaf architecture, every leaf switch connects to every spine switch, and spine switches do not connect directly to each other. This creates a uniform bipartite topology where any endpoint on a leaf switch reaches an endpoint on another leaf switch in exactly three hops (Leaf -> Spine -> Leaf), yielding consistent and predictable latency for East-West traffic.

Step-by-Step Solution

1
Analyze Spine-Leaf physical connectivity rules
Confirm that Spine-Leaf fabrics require a bipartite connection pattern where leaf switches connect to all spine switches, while spine-to-spine and leaf-to-leaf direct links are omitted.
This structural pattern allows Equal-Cost Multi-Pathing (ECMP) to load-balance traffic dynamically across all available spine paths.
2
Evaluate traffic path consistency for East-West data flows
Determine that any leaf-to-leaf communication crosses exactly one spine switch.
Uniform path lengths prevent latency variance for inter-server communication.
3
Evaluate attachment points for endpoints and hypervisors
Identify that servers, hypervisors, and security appliances attach strictly to leaf switches (access layer of the fabric).
Attaching hosts to spine switches breaks the bipartite Clos architecture and compromises ECMP forwarding.

Key Concept

Spine-Leaf Topology Connectivity & Traffic Dynamics
Estimated Time:1m 30s
Question 9Question →

Match each network topology architecture to its corresponding structural design trait and traffic flow optimization behavior.

Click a left item, then click its matching right item

Items

Routed Access 3-Tier Campus Architecture
Spine-Leaf (Clos) Data Center Architecture
Collapsed Core 2-Tier Architecture
Traditional Layer 2 Access 3-Tier Architecture

Matches

Show answer & explanation

Answer

Routed Access 3-Tier Campus Architecture pairs with terminating VLANs at the access switch using IGP routing. Spine-Leaf Data Center Architecture pairs with predictable single-hop latency via a bipartite non-interconnected tier design. Collapsed Core 2-Tier Architecture pairs with consolidating core routing and aggregation into a unified switch pair. Traditional Layer 2 Access 3-Tier Architecture pairs with extending VLANs across access switches requiring STP loop blocking.
Each topology pattern is accurately matched based on its architectural boundaries and operational characteristics: Routed Access eliminates STP on uplinks via Layer 3 edge routing; Spine-Leaf uses a bipartite design for consistent East-West latency; Collapsed Core combines core and aggregation layers to save cost; and Traditional Layer 2 Access relies on STP to block redundant Layer 2 uplinks.

Step-by-Step Solution

1
Analyze the Layer 2/Layer 3 boundary for Routed Access.
In a Routed Access model, routing occurs at the access switch, so uplinks are routed point-to-point links. This eliminates Layer 2 loops and Spanning Tree Protocol blocking on uplinks.
Moving the routing boundary to the access switch limits broadcast domains to a single switch.
2
Evaluate the connectivity rules of Spine-Leaf (Clos) topologies.
Spine-Leaf uses a bipartite graph (leaf switches connect to all spines; spine switches connect to all leaves; no intra-tier links).
This guarantees equal distance (two hops) and equal-cost multi-pathing (ECMP) for East-West server traffic.
3
Examine the physical consolidation in a Collapsed Core design.
A Collapsed Core merges Distribution (policy/aggregation) and Core (high-speed transport) into a single layer.
This reduces equipment count, cabling complexity, and cost for smaller deployment environments.
4
Identify the primary operational requirement of Traditional Layer 2 Access designs.
Extending Layer 2 VLANs across multiple access switches to distribution switches creates Layer 2 loops across redundant uplinks.
Spanning Tree Protocol must block redundant paths to maintain a loop-free topology.

Key Concept

Comparison of Enterprise Campus and Data Center Network Topology Architectures
Question 10Question →

Match each network architecture layer or topology design model on the left to its correct functional responsibility or operational trait on the right.

Click a left item, then click its matching right item

Items

Spine Layer (Data Center Spine-Leaf)
Leaf Layer (Data Center Spine-Leaf)
Distribution Layer (Traditional 3-Tier Campus)
Collapsed Core Layer (2-Tier Campus)

Matches

Show answer & explanation

Answer

Spine Layer matches high-speed L3 ECMP backbone forwarding; Leaf Layer matches endpoint attachment and VTEP encapsulation; Distribution Layer matches inter-VLAN routing, ACL filtering, and policy enforcement; Collapsed Core matches combining Core transport and Distribution policy into a single switch tier.
The pairings correctly align each tier with its defining design attributes: Spine switches provide non-blocking ECMP L3 transport; Leaf switches act as endpoint connection points and VTEPs; Distribution switches manage L2/L3 policy, ACLs, and routing boundaries; Collapsed Core switches combine Core and Distribution capabilities into one physical tier.

Step-by-Step Solution

1
Analyze Spine Layer responsibilities in Data Center Spine-Leaf (Clos) design.
Spine switches strictly interconnect Leaf switches, run L3 routing protocols, and provide equal-cost multipath transport without inter-spine links.
Spine nodes form the high-speed backbone core of the Clos fabric.
2
Analyze Leaf Layer responsibilities in Spine-Leaf design.
Leaf switches connect to servers, storage, and firewalls, serving as the edge access and VTEP overlay encapsulation boundary.
Endpoints attach exclusively to Leaf nodes in modern fabric architectures.
3
Analyze Distribution Layer responsibilities in traditional 3-Tier Campus design.
Distribution switches aggregate Access switches, perform inter-VLAN routing, and enforce security ACLs and QoS policies.
The Distribution tier isolates the Access tier from the Core tier and manages network policies.
4
Analyze Collapsed Core (2-Tier) campus design characteristics.
Collapsed Core integrates Distribution policy routing and Core high-speed switching into one combined physical tier.
It simplifies deployment for smaller networks that do not require separate core and distribution switch chassis.

Key Concept

Enterprise Campus (3-Tier & Collapsed Core) vs. Data Center (Spine-Leaf) Architectural Layers
Question 11Question →

An enterprise network operations team is replacing a legacy 3-Tier campus architecture with a 2-Tier Spine-Leaf (Clos) topology in their data center to optimize East-West traffic performance for containerized microservices. Which of the following architectural characteristics and operational design principles correctly describe this Spine-Leaf fabric when compared to the traditional 3-Tier model? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: Every Leaf switch connects to every Spine switch in a full mesh layout, guaranteeing a deterministic two-hop latency path for inter-leaf traffic.; Equal-Cost Multi-Pathing (ECMP) routing is implemented across Layer 3 uplinks to enable active-active load sharing without Spanning Tree Protocol port blocking.

Answer

The correct statements are that every Leaf switch connects directly to every Spine switch to provide a deterministic two-hop path for inter-leaf traffic, and that Layer 3 routing with Equal-Cost Multi-Pathing (ECMP) enables active-active load balancing across uplinks without Spanning Tree Protocol link blocking.
In a 2-Tier Spine-Leaf fabric, every Leaf switch connects directly to every Spine switch without horizontal intra-tier links. This structural layout provides a predictable two-hop transport path for East-West traffic across Leaf switches. Furthermore, deploying Layer 3 routing with Equal-Cost Multi-Pathing (ECMP) allows active-active forwarding across all Leaf-Spine links, eliminating Spanning Tree Protocol blocking.

Step-by-Step Solution

1
Analyze physical cabling topology constraints in a 2-Tier Spine-Leaf (Clos) architecture.
Verify that Spine-Leaf requires every Leaf node to connect to every Spine node, with zero direct links between nodes of the same tier.
This bipartite graph layout ensures a predictable, fixed path length of exactly two hops (Leaf to Spine to Leaf) for any East-West communication.
2
Evaluate control plane mechanisms and bandwidth utilization across the fabric.
Determine that Layer 3 routing combined with ECMP replaces Layer 2 Spanning Tree Protocol loop-prevention mechanisms.
ECMP utilizes all available uplinks simultaneously in an active-active forwarding state, avoiding the bandwidth degradation caused by STP port blocking.
3
Differentiate device roles and boundary placements between Leaf and Spine switches.
Confirm that end-system access ports and broadcast domain boundaries reside strictly on Leaf switches, while Spine switches act solely as high-speed transport infrastructure.
Isolating Spine switches from direct host connectivity and Layer 2 broadcast domains keeps the core stateless, fast, and scalable.

Key Concept

2-Tier Spine-Leaf (Clos) Architecture Characteristics vs 3-Tier Campus Design
Question 12Question →

Match each network topology architecture model or functional layer on the left to its corresponding design trait and operational responsibility on the right.

Click a left item, then click its matching right item

Items

Collapsed Core Architecture Layer
Three-Tier Core Layer
Three-Tier Distribution Layer
Data Center Spine Layer (Clos)

Matches

Show answer & explanation

Answer

Collapsed Core Architecture Layer matches the description combining core transport and policy enforcement into a single switch pair. Three-Tier Core Layer matches the description providing high-speed transport without CPU-intensive packet inspection or ACL filtering. Three-Tier Distribution Layer matches the description aggregating Access switches, acting as the L2/L3 boundary, and enforcing security policies. Data Center Spine Layer matches the description functioning as a high-bandwidth IP fabric backbone with predictable single-hop latency.
Each architecture layer is uniquely optimized for its operational domain: Collapsed Core combines distribution and core functions for smaller networks; Three-Tier Core optimizes raw forwarding speed without packet filtering; Three-Tier Distribution acts as the control boundary for VLANs, security policies, and routing aggregation; Spine-Leaf Spine nodes provide predictable, non-blocking single-hop transport between all leaf switches.

Step-by-Step Solution

1
Analyze the functional responsibilities of campus network layers.
Identify that the Core layer focuses exclusively on transport speed, while the Distribution layer handles routing boundaries, ACLs, and policy enforcement.
Separation of duties in campus designs prevents performance bottlenecks on the core backbone.
2
Evaluate the Collapsed Core model.
Recognize that Collapsed Core integrates core switching and distribution policies into one physical tier, suited for medium enterprise designs.
Combining layers lowers equipment cost while retaining high availability.
3
Examine data center Spine-Leaf (Clos) architectural dynamics.
Distinguish that Spine switches form a full mesh fabric with Leaf switches to optimize east-west server traffic with deterministic latency.
Spine switches do not connect to each other; they strictly interconnect leaf nodes across a non-blocking Layer 3 fabric.

Key Concept

Network Architectural Layer Functional Responsibilities and Design Trade-offs
Question 13Question →

A network technician is reviewing the physical and logical layout of a small branch office network that uses a 2-Tier (Collapsed Core) campus topology. Which two statements accurately describe key characteristics of this topology architecture? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: The core layer and distribution layer functions are combined into a single set of switches.; Access switches connect directly to the collapsed core/distribution devices.

Answer

The two correct traits of a 2-Tier (Collapsed Core) campus topology are that core and distribution layer functions are combined into unified switches, and access switches connect directly to these collapsed core/distribution devices.
In a 2-Tier (Collapsed Core) architecture, the traditional core and distribution layers are combined into a single switch tier, allowing access switches to connect directly to the collapsed core. This minimizes cost and maintenance while providing essential Layer 2/Layer 3 redundancy and connectivity.

Step-by-Step Solution

1
Identify the defining structural characteristic of a 2-Tier campus architecture.
The core layer and distribution layer are merged (collapsed) into a single functional layer.
This reduces hardware cost, management overhead, and cabling complexity for smaller networks.
2
Determine how access layer devices connect within this architecture.
Access switches uplink directly into the collapsed core switches.
Since there is no standalone distribution tier, the access switches connect straight to the combined core/distribution layer.

Key Concept

2-Tier (Collapsed Core) Network Topology Architecture
Question 14Question →

In a standard two-tier Spine-Leaf data center architecture, to which switches does every leaf switch directly connect?

Show answer & explanation

Answer: To every spine switch in the network fabric

Answer

Every leaf switch connects directly to every spine switch in the network fabric.
In a Spine-Leaf (Clos) architecture, every leaf switch connects to every spine switch in a full mesh layout between tiers. Leaf switches do not connect to each other, nor do spine switches connect to each other. This design provides consistent latency and maximum redundancy.

Step-by-Step Solution

1
Identify the structural rule of a two-tier Spine-Leaf (Clos) data center topology.
In a two-tier Spine-Leaf architecture, every leaf switch must connect to every spine switch in the fabric.
This guarantees equal path distance (predictable latency) and maximum bandwidth between any two leaf switches.
2
Verify inter-switch connection rules within the leaf and spine layers.
Leaf switches do not connect directly to other leaf switches, and spine switches do not connect directly to other spine switches.
Maintaining strict bipartite connectivity ensures efficient Equal-Cost Multi-Path (ECMP) routing across all available paths.

Key Concept

Spine-Leaf Architecture Bipartite Connectivity
Estimated Time:45s
Question 15Question →

An enterprise network architect is migrating a primary data center from a traditional 3-Tier (Access-Aggregation-Core) hierarchy to a 2-Tier Spine-Leaf (Clos) architecture to better handle high-volume East-West microservices traffic. Which TWO statements correctly describe the design rules and operational characteristics of this Spine-Leaf topology? (Choose two.)

Select all that apply

Show answer & explanation

Answer: Every leaf switch connects to every spine switch, but leaf switches do not connect directly to other leaf switches.; Equal-Cost Multi-Path (ECMP) routing is leveraged across Layer 3 links to utilize all available bandwidth concurrently between leaf and spine switches.

Answer

The correct statements are that every leaf switch connects to every spine switch without direct leaf-to-leaf connections, and that Equal-Cost Multi-Path (ECMP) routing is utilized to load-balance traffic across all available links.
In a 2-Tier Spine-Leaf design, the fabric forms a bipartite graph where every leaf switch connects to every spine switch, with no direct connections between switches of the same tier. Traffic between leaves passes through spine switches using Layer 3 routing and Equal-Cost Multi-Path (ECMP), enabling deterministic low-latency, active-active forwarding across all available links.

Step-by-Step Solution

1
Analyze physical connectivity rules in a 2-Tier Spine-Leaf (Clos) architecture.
Leaf switches connect to all spine switches in a full mesh (bipartite graph). Leaves do not connect to leaves, and spines do not connect to spines.
Ensures predictable latency where every access point is exactly two hops away from any other access point.
2
Evaluate control plane forwarding mechanisms between leaf and spine nodes.
Layer 3 routing protocols are implemented across interswitch links to enable Equal-Cost Multi-Path (ECMP).
ECMP enables active-active packet forwarding over all physical links, avoiding the link blocking penalties of traditional Layer 2 STP topologies.
3
Identify misconceptions regarding Layer 2 switching and PortFast configuration on interswitch links.
STP blocking and PortFast on trunk links are inappropriate for leaf-spine interconnects.
Layer 3 forwarding prevents STP loops organically, and applying PortFast on switch trunks risks bridging loops.

Key Concept

Spine-Leaf (Clos) Topology Connectivity Rules and ECMP Forwarding
Estimated Time:2m 0s
Question 16Question →

An enterprise organization with 40 remote branch sites needs to connect all sites to a central data center. Direct communication between branch sites is rarely required, but predictable bandwidth to the central data center and minimal WAN circuit licensing costs are strict requirements. If a single branch WAN link fails, only that site should lose connectivity. Which WAN topology architecture best meets these operational and financial requirements?

Show answer & explanation

Answer: Hub-and-spoke topology

Answer

The hub-and-spoke topology best satisfies the requirements by concentrating connections at the central hub, minimizing total WAN circuit costs, and isolating individual branch link failures.
The hub-and-spoke topology connects each remote branch directly to a central hub (the data center). This provides independent connectivity per branch, requires only one WAN link per branch site, and minimizes overall cost while aligning perfectly with centralized traffic patterns.

Step-by-Step Solution

1
Analyze WAN traffic flow requirements
Traffic flow is primarily client-to-server (branch-to-central data center), with minimal branch-to-branch communication required.
Understanding traffic flows dictates whether direct site-to-site WAN circuits are necessary.
2
Evaluate cost and link scaling across candidate topologies
A hub-and-spoke design scales linearly with N−1N-1 links (39 links for 40 sites), whereas a full-mesh design requires 40×392=780\frac{40 \times 39}{2} = 780 links.
Minimizing WAN circuit licensing and circuit operational expenditure requires choosing a cost-efficient topology.
3
Verify fault domain isolation capabilities
In a hub-and-spoke architecture, each spoke operates on its own WAN connection to the hub, so a failure on one spoke circuit affects only that specific branch.
Ring and linear/daisy-chain topologies risk impacting multiple downstream sites upon a single link outage.

Key Concept

WAN Topology Architectures (Hub-and-Spoke vs Mesh vs Ring)
Estimated Time:2m 0s
Question 17Question →

An network administrator is setting up a traditional Cisco three-tier campus network. Which network tier is primarily responsible for directly attaching workstations, IP phones, and wireless access points while providing boundary security features such as port security?

Show answer & explanation

Answer: Access layer

Answer

The Access layer is responsible for direct endpoint connectivity and edge security control.
In a classic three-tier hierarchical campus network design, the Access layer switch provides direct physical and logical connectivity for end-user devices (workstations, printers, IP phones) and implements local port-level security features like Port Security and DHCP Snooping.

Step-by-Step Solution

1
Identify the primary functions required in the prompt
Directly connecting end-user endpoints (workstations, IP phones, APs) and applying edge security features such as port security.
Different network layers in Cisco hierarchical designs perform distinct operational tasks.
2
Map these functions to the correct Cisco three-tier layer
The Access layer provides end-node attachment and initial entry controls.
The Core layer focuses purely on high-speed switching, while the Distribution layer manages routing boundaries and aggregation.

Key Concept

Cisco 3-Tier Campus Architecture - Access Layer Role
Estimated Time:45s
Question 18Question →

A network architect is designing a two-tier spine-leaf data center fabric. Each of the 8 leaf switches connects to 48 edge servers using 10 Gbps access ports, generating 480 Gbps480\text{ Gbps} of potential access bandwidth per switch. The design policy mandates a maximum bandwidth oversubscription ratio of 3:13:1 across the spine fabric. If all spine and leaf interconnect interfaces operate at 40 Gbps, which architecture satisfies the oversubscription constraint while adhering to standard Clos topology rules?

Show answer & explanation

Answer: Deploy 4 spine switches and connect each leaf switch with a single 40 Gbps link to every spine switch.

Answer

Deploying 4 spine switches where each leaf switch has a single 40 Gbps uplink to every spine switch correctly provides 160 Gbps of uplink capacity per leaf (meeting the 3:1 oversubscription ratio) and strictly obeys Spine-Leaf bipartite graph connectivity rules.
Each leaf switch requires 480 Gbps/3=160 Gbps480\text{ Gbps} / 3 = 160\text{ Gbps} of uplink bandwidth to achieve a 3:13:1 oversubscription ratio. Using 40 Gbps links, each leaf switch needs 4 uplinks. Standard Spine-Leaf design rules dictate that every leaf switch must connect to every spine switch, and spine switches must not connect to one another. Therefore, deploying 4 spine switches with 1 link from each leaf to each spine satisfies both bandwidth and topological requirements.

Step-by-Step Solution

1
Calculate total access bandwidth per leaf switch
48×10 Gbps=480 Gbps48 \times 10\text{ Gbps} = 480\text{ Gbps} access bandwidth per leaf switch.
Determining total ingress/egress access capacity is required to calculate uplink oversubscription.
2
Calculate required uplink bandwidth based on the 3:1 oversubscription ratio limit
Required Uplink Bandwidth=480 Gbps3=160 Gbps\text{Required Uplink Bandwidth} = \frac{480\text{ Gbps}}{3} = 160\text{ Gbps}.
A 3:13:1 oversubscription ratio means uplink bandwidth must be at least one-third of the access bandwidth.
3
Determine the number of 40 Gbps uplinks required per leaf switch
160 Gbps40 Gbps=4\frac{160\text{ Gbps}}{40\text{ Gbps}} = 4 uplink connections per leaf switch.
Interconnect ports run at 40 Gbps, so 4 ports are required to achieve 160 Gbps total uplink capacity.
4
Apply Clos (Spine-Leaf) architectural connectivity rules
Deploy 4 spine switches and connect each leaf switch to every spine switch using exactly one 40 Gbps uplink.
In a 2-Tier Spine-Leaf topology, every leaf connects to every spine, spines do not connect to spines, and leaves do not connect to leaves.

Key Concept

Spine-Leaf (Clos) Topology Oversubscription and Fabric Interconnect Rules
Estimated Time:2m 0s
Question 19Question →

Match each network topology architecture to its corresponding operational characteristic and traffic flow optimization profile.

Click a left item, then click its matching right item

Items

Spine-Leaf (Clos) Fabric
Traditional 3-Tier Campus
Collapsed Core (2-Tier)
WAN Hub-and-Spoke

Matches

Show answer & explanation

Answer

Spine-Leaf (Clos) Fabric matches with East-West low-latency traffic using ECMP; Traditional 3-Tier Campus matches with separate functional tiers for structured North-South flow; Collapsed Core matches with combining core and distribution functions into a single switch pair; WAN Hub-and-Spoke matches with centralizing inspection and routing remote branch traffic through a central hub site.
Each topology architecture addresses specific scalability, redundancy, and traffic flow requirements: Spine-Leaf optimizes East-West data center flows using ECMP over a two-tier bipartite mesh; Traditional 3-Tier structures campus environments into distinct access, distribution, and core roles for policy control; Collapsed Core merges core and distribution layers for smaller networks to lower cost; WAN Hub-and-Spoke centralizes security and reduces link costs by routing branch-to-branch traffic through a central hub.

Step-by-Step Solution

1
Analyze the structural traffic requirements of modern data center versus campus environments.
Identified that Spine-Leaf designs specifically target East-West (server-to-server) traffic via non-blocking ECMP routing across spine switches.
Data center workloads require low, deterministic latency across leaf switches regardless of physical placement.
2
Evaluate the functional division of campus topologies.
Identified that 3-Tier Campus separates core, distribution, and access, placing policy enforcement at the distribution layer, whereas Collapsed Core merges core and distribution into a single switch pair for smaller footprints.
Merging layers reduces cost in smaller networks, while dedicated tiers scale policy enforcement in larger enterprise networks.
3
Examine wide area network (WAN) deployment topologies.
Identified Hub-and-Spoke as the topology that centralizes policy enforcement and minimizes WAN link costs by routing all branch communications through a central hub.
Full mesh topologies require far more connections, making hub-and-spoke cost-effective when central security inspection is required.

Key Concept

Enterprise Network Topology Architectures and Traffic Flow Characteristics
Estimated Time:1m 30s
Question 20Question →

A network engineer is designing a topology for a branch office with approximately 150 users across two floors. To minimize capital expenditure and management overhead while maintaining VLAN redundancy and routing capabilities between local subnets, the engineer selects a Cisco Collapsed Core topology instead of a traditional Cisco Three-Tier hierarchy. Which architectural modification defines this Collapsed Core implementation?

Show answer & explanation

Answer: The core layer and distribution layer functions are consolidated into a single pair of switches.

Answer

The core layer and distribution layer functions are consolidated into a single pair of switches.
The defining characteristic of a Cisco Collapsed Core (two-tier) architecture is merging the core and distribution layers into a single pair of switches. This maintains key Layer 3 routing, policy enforcement, and redundancy functions while reducing overall equipment cost and administration complexity for small to medium enterprise sites.

Step-by-Step Solution

1
Analyze the requirements of the branch office network design
The scenario requires connecting 150 users efficiently while reducing costs and complexity compared to a full three-tier campus design.
Smaller sites do not have sufficient scale or port-density demands to justify separate Core and Distribution switch pairs.
2
Compare traditional Three-Tier architecture against Collapsed Core (Two-Tier) architecture
A traditional Three-Tier topology consists of distinct Access, Distribution, and Core layers. A Collapsed Core merges the Core (high-speed transport) and Distribution (routing, ACLs, policy enforcement) responsibilities into one tier.
Consolidating these two layers into a single switch pair (collapsed core switches) provides Layer 3 boundaries and inter-VLAN routing while decreasing hardware footprint.

Key Concept

Cisco Collapsed Core Topology Architecture
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