400-007 Exam Dumps - Cisco Certified Design Expert (CCDE v3.1)

SD-WAN integrates multiple underlay transport options (Internet, MPLS, LTE) while delivering advanced features like DPI (Deep Packet Inspection), SLA monitoring, QoS, encryption, scalability, and centralized management.

It provides policy-based path selection, cost optimization, and rapid deployment.

SD-WAN is widely regarded as a modern WAN design solution fully aligned with CCDE v3.1 design principles for cost-effective and flexible WAN architectures.

Why other options are incorrect:

B: Internet alone cannot deliver consistent SLA or QoS guarantees.

C: Hybrid MPLS + Internet may work but is more complex and costly; SD-WAN natively supports such hybrid models.

D: MPLS offers SLAs but lacks flexibility, DPI, and cost-effectiveness compared to SD-WAN.

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C (Accountability for ROI):Shifting focus toward ROI ensures that capital investment is evaluated based on business impact rather than just financial outputs like revenue and EBITDA, aligning technology spending with business value.

Other options explained:

A: Financial reporting doesn't address accountability.

B: Misrepresents leadership responsibility.

D: Budget cuts don’t address the structural root cause.

To conserve IPv4 addresses and achieve fast convergence:

B: Using /31 subnets for point-to-point (P2P) links enables each link to consume only two IP addresses. This is widely supported and conserves address space.

C: A hub-and-spoke design with P2P links minimizes the number of neighbor relationships and simplifies routing convergence.

Other options:

A: Multipoint Metro-E introduces neighbor adjacency complexity and DR/BDR elections, which delay convergence.

D: Aggregation is more applicable to prefix summarization, not address conservation per link.

E: DR/BDR roles apply only in broadcast/multicast environments, not P2P links.

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MLD (Multicast Listener Discovery) snooping for IPv6 operates similarly to IGMP snooping in IPv4. It tracks listener reports to restrict multicast flooding within a Layer 2 domain.

C: Querier elections are triggered when a querier becomes unreachable or its IP address changes.

D: The querier with the lowest IPv6 address is elected as the active querier, which manages report/query communication.

Other options:

A: QoS is not automatically enabled with MLD snooping.

B: MLD querier functionality operates per VLAN—not per group—so only one querier is elected per VLAN.

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The root cause here is likely related to multicast forwarding behavior:

Multicast forwarding may follow a single path based on unicast routing decisions (shortest-path trees or RPF lookup).

Equal-cost Layer 3 links do not always achieve perfect load balancing for multicast traffic since the multicast flow may hash consistently to a particular path.

Applying a more granular load-balancing hash algorithm on SW1 allows better distribution of flows across multiple links by considering additional packet header fields (e.g., Layer 4 ports, source/destination IP).

This is directly aligned with CCDE v3.1 design goals:

Avoiding overutilization by improving hashing entropy.

Preserving consistent unicast and multicast performance.

Leveraging hardware-based load balancing optimizations.

Why other options are incorrect:

A & B: Adding or bundling links doesn't address poor hashing distribution.

D: The issue is identified at SW1 (where hashing decisions are made).

E: Filtering IGMP joins may block legitimate receivers, not a valid solution.

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B (R1 adjusts to R2’s Required Min RX):In BFD, each side advertises itsDesired Min TX IntervalandRequired Min RX Interval. Each device adjusts its transmission interval to match the remote side’s ability to receive packets (Required Min RX). So R1 reduces its transmission rate to 100 ms to match R2's platform limitations.

Other options explained:

A: R2 does not adjust to R1’s Desired Min TX; it’s the sender who adapts.

C: BFD quickly converges after initial negotiation.

D: P-bit and F-bit are not involved in this specific interval negotiation.

Comprehensive and Detailed Explanation From Exact Extract of Design Expert (CCDE)

Summarization reduces control plane state by abstracting detailed route information. As packets move further away from the destination subnet, the network advertises summarized prefixes instead of individual host or subnet routes, minimizing control plane overhead and routing table size. This helps scale large networks and improves convergence times.

While aggregation and summarization are related, summarization specifically refers to the propagation of route prefixes and their abstraction — making it the precise fit for this question.

ChatGPT said:🟦 QUESTION NO: 391

[Main Topic: Scenario-Based Design Strategy Guidance]

Feature-rich and attributed networks are used to model complex systems where nodes and links can represent various relationships and characteristics. Which two alternative network models can be used to model interactions over time or by specific relationships?

A. heterogeneous network

B. information network

C. location-aware network

D. multilayer network

E. probabilistic network

F. temporal network

Answer: D, F

🔍Comprehensive Explanation:

D. Multilayer Network:This model captures different types of relationships or interactions by separating them into layers. Each layer can represent a specific attribute (e.g., organizational structure, communication paths, or access levels), enabling a more granular view of network behaviors or dependencies.

F. Temporal Network:A temporal network models interactions over time by including timestamps or time intervals for each interaction or link. It’s well-suited for analyzing dynamic behaviors such as traffic flow, communication logs, or transaction timelines.

Other options:

❌A. Heterogeneous Network: Refers to networks composed of different technologies or platforms, not necessarily different types of attributes or timelines.

❌B. Information Network: This is a general term and does not specifically define a structured modeling approach for attributes or time.

❌C. Location-Aware Network: Involves geolocation or spatial data but does not inherently model time or multi-attribute structures.

❌E. Probabilistic Network: Uses probability distributions to model uncertain events, not ideal for modeling time or attributes.

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🟦 QUESTION NO: 392

[Main Topic: Business-Driven Design Approaches]

A company is assessing their technology landscape before moving to the cloud. They observe that over 5000 servers have less than 50% capacity utilization. What cloud architecture model best supports optimizing resource utilization?

A. homogenous cloud

B. heterogenous cloud

C. hybrid-private cloud

D. public cloud

Answer: D

🔍Comprehensive Explanation:

D. Public Cloud:Public cloud services provide elastic and scalable infrastructure. For workloads with low or variable utilization, public cloud offers pay-as-you-go models that significantly reduce the overhead of underutilized on-prem hardware. This is ideal for shifting capital expenditure (CAPEX) to operational expenditure (OPEX), achieving better cost efficiency.

Other options:

❌A. Homogenous Cloud: Not a standard term; it might imply uniform hardware/software environments, but it doesn’t address utilization.

❌B. Heterogenous Cloud: Typically used to describe mixed environments but doesn’t directly offer utilization optimization.

❌C. Hybrid-Private Cloud: Offers flexibility and data control but still often involves maintaining some level of underused on-prem resources unless carefully managed.