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

Bit Indexed Explicit Replication (BIER) eliminates the need for traditional multicast signaling protocols such as PIM.

BIER uses IGP extensions (e.g., OSPF or ISIS) to advertise BIER forwarding state.

The BIER header contains a bit-string indicating directly which receivers should receive the multicast packet, removing the need to build trees via signaling.

This design is emphasized in CCDE v3.1 as a significant advancement for efficient, scalable multicast in large modern service provider and enterprise networks.

Why other options are incorrect:

A, B, D: These options are invalid or fictitious terms in multicast protocol standards.

C (Push-based): Push notifications to a registered device (typically a phone) are used as a second authentication factor.

D (Possession-based): Possession factor includes physical tokens, smart cards, or registered devices — verifying that the user possesses something unique.

Other options explained:

A/B/E: Not valid MFA factors under standard authentication frameworks.

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

Agile practices and DevOps principles are foundational to infrastructure modernization. Agile enables iterative development, collaboration, and responsiveness to change, while DevOps unifies development and operations, fostering automation, monitoring, and continuous delivery. These elements improve not just technical efficiency but also cultural alignment across teams, boosting productivity and adaptability.

Infrastructure-as-code (Option B) supports automation but is an enabler—not a cultural component by itself. Controlled and dedicated infrastructure reflects traditional IT models that lack agility and flexibility.

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Comprehensive and Detailed Explanation:

A: PaaS (Platform as a Service) solutions often introduce strong vendor-specific APIs, services, and tooling, making it difficult to migrate applications later—leading to vendor lock-in.

Other options:

B and C apply more to SaaS and IaaS models.

D: Multi-tenant security concerns are common in all models but not unique or predominant in PaaS.

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Comprehensive and Detailed Explanation:

B: Augmented SDN allows external applications or controllers to interact with the traditional control plane (e.g., RIB or FIB) via APIs, without fully replacing it.

A (replace) removes traditional control protocols entirely.

C (hybrid) uses both SDN and legacy control planes, but without deep integration.

D (distributed) refers to traditional decentralized control planes.

Augmented SDN enhances traditional routing with programmable control, offering near real-time visibility and dynamic response without disrupting the existing control architecture.

When OSPF operates over a broadcast network (such as Ethernet), it uses the DR (Designated Router) and BDR (Backup Designated Router) mechanism to reduce adjacency overhead. Instead of forming full mesh adjacencies, OSPF routers establish full neighbor relationships only with the DR and BDR.

For five routers:

Each router establishes a full adjacency with the DR and the BDR.

The DR and BDR also establish adjacency with each other.

Total number of fully established adjacencies = 5 (each router to DR/BDR).

Partial adjacencies (2-way) may exist among DROther routers, but those are not fully established neighbor relationships (i.e., not exchanging LSDBs).

This design behavior is emphasized in CCDE v3.1 to avoid excessive LSDB flooding and optimize control-plane scaling.

Why other options are incorrect:

B, C, D, E: These assume full mesh adjacencies or incorrect OSPF behavior for broadcast networks.

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Encrypting data at rest and in transit is a fundamental best practice to ensure end-to-end data security.

It protects sensitive data both while stored (disk, database) and while moving across networks.

Why other options are incorrect:

A: IPsec secures specific tunnels, but isn’t a complete private cloud solution.

C: Vendor consistency doesn’t guarantee best practice.

D: Anonymization supports privacy but is not a core security best practice for data security.

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Comprehensive and Detailed Explanation:

B: Fate sharing refers to a situation where multiple logical or virtual paths depend on a single physical component. If that physical link fails, all virtual tunnels or services carried over it are simultaneously affected—reducing fault isolation and increasing failure impact.

Other options:

A: Tunneling is often needed for overlays; not inherently a drawback.

C: Bandwidth utilization is an efficiency metric, not a drawback in this context.

D: Serialization delay is more relevant to low-speed links or voice/real-time traffic, not virtualized path concerns.

????   QUESTION NO: 338 [Protocol Design Implications]

An engineer must redesign the QoS strategy due to oversubscription and excessive packet drops. What QoS technique should be used to manage traffic leaving the edge router and reduce packet drops?

A. LLQ

B. Traffic shaping

C. Rate-limiting

D. Policing

Answer: B

????   Explanation:

B: Traffic shaping buffers excess traffic and releases it gradually to match the configured rate, preventing congestion and dropped packets on outbound interfaces. It’s ideal for controlling egress traffic to match the service provider's rate.

Other options:

A: LLQ (Low Latency Queueing) provides strict priority queuing but doesn’t control overall rate or prevent oversubscription.

C: Rate-limiting enforces a cap and drops packets exceeding the threshold.

D: Policing drops excess traffic immediately and is more aggressive than shaping.

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????   QUESTION NO: 339 [Scenario-Based Design Strategy Guidance]

Refer to the exhibit. The network experiences Stuck-in-Active (SIA) problems due to resource contention. An acquisition will further increase routing demands via R3 and R4.

Which solution best mitigates the SIA issue?

A. Utilize EIGRP unequal cost load-balancing on R5 and R6

B. Implement EIGRP Route Flap Dampening

C. Deploy EIGRP stub on R5 and R6 with connected and summary options

D. Advertise only a default route to R5 and R6

Answer: C

????   Explanation:

C: Configuring R5 and R6 as EIGRP stub routers reduces query scope and prevents SIA conditions. EIGRP stub routers do not forward queries and are ideal for spoke or edge routers.

Other options:

A: Load balancing doesn’t reduce control-plane query overhead.

B: Route Flap Dampening isn’t applicable to EIGRP and won’t solve SIA.

D: Default route advertisement helps simplify routing, but stub configuration is purpose-built to prevent SIA issues.

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????   QUESTION NO: 340 [Security, Automation, and Policy Integration in Design]

Which are two benefits of using Layer 2 access control lists (ACLs) for segmentation? (Choose two)

A. Traffic filtering

B. Contextual filtering

C. Containing lateral attacks

D. Reduced load at Layer 2

E. VLAN intercept

Answer: A, C

????   Explanation:

A: Layer 2 ACLs can block or allow specific MAC or IP traffic right at the switchport.

C: Containing lateral attacks—Layer 2 ACLs help block unauthorized east-west traffic between hosts within the same VLAN.

Incorrect options:

B: Contextual filtering is associated with next-gen firewalls or Layer 7 inspection.

D: ACLs add processing load, not reduce it.

E: VLAN intercept is not a valid Cisco term for ACL application.

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????   QUESTION NO: 341 [Business-Driven Design Approaches / Agile Frameworks]

In the Scrum Agile framework, who acts as the interface between the business/customers and the team?

A. Product Owner

B. Product Manager

C. Scrum Master

D. Program Manager

Answer: A

????   Explanation:

A: The Product Owner is responsible for defining user stories, maintaining the product backlog, and representing the customer's voice to the development team.

B: Product Manager may define broader strategy but doesn’t manage the backlog directly.

C: Scrum Master ensures the process is followed but doesn’t interface with the business side.

D: Program Manager oversees multiple projects; not Scrum-specific.

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????   QUESTION NO: 342 [Security, Automation, and Policy Integration in Design]

Company XYZ must isolate and encrypt production traffic to meet HIPAA compliance. The current WAN includes MPLS and P2P links.

What is the fastest deployment option?

A. IPsec P2P tunnels over MPLS and links

B. GETVPN over MPLS

C. Centralized firewall

D. VRF-Lite with IPsec tunnels

Answer: A

????   Explanation:

A: IPsec point-to-point tunnels provide immediate, well-supported encryption across both MPLS and P2P transports. Quick to implement and doesn’t rely on service provider support.

Other options:

B: GETVPN requires coordination and is more complex to deploy.

C: Central firewalls don’t encrypt traffic over the WAN.

D: VRF-Lite with IPsec is viable but more complex than direct IPsec tunnels.

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????   QUESTION NO: 343 [Technology Comparisons and Use Cases]

One of the approaches used in cloud bursting is distributed load-balancing, where workloads operate between a public cloud and a data center.

How can the characteristics of distributed load-balancing be described?

A. Simultaneously provisions cloud resources

B. Usually uses cloud APIs for communication

C. Useful for testing and proof-of-concept projects

D. Useful for large but temporary cloud deployments

Answer: A

????   Explanation:

A: Distributed load-balancing in cloud bursting allows workloads to run simultaneously across on-premises infrastructure and public cloud. Resources are provisioned concurrently to manage increased load or optimize application performance.

Other options:

B: Cloud APIs are widely used, but this is a general trait of cloud integration—not specific to distributed load-balancing.

C: Proof-of-concept projects are more aligned with basic cloud testing or DevOps, not distributed production workloads.

D: Temporary deployments describe elastic scaling, not the permanent load-balancing between environments.

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????   QUESTION NO: 344 [Business-Driven Design Approaches]

Which two factors must be considered while calculating the Recovery Time Objective (RTO)? (Choose two)

A. Importance and priority of individual systems

B. Maximum tolerable amount of data loss that the organization can sustain

C. Cost of lost data and operations

D. How often backups are taken and how quickly these can be restored

E. Steps needed to mitigate or recover from a disaster

Answer: A, C

????   Explanation:

A: RTO depends on how critical the system is. More critical systems require shorter recovery times.

C: The business impact of downtime (cost of operational loss) drives the acceptable RTO for systems.

Incorrect options:

B: This refers to Recovery Point Objective (RPO), not RTO.

D: Backup frequency aligns with RPO; restore speed can influence RTO but isn't a direct calculation input.

E: Mitigation steps are part of disaster recovery planning—not direct RTO calculation.

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????   QUESTION NO: 345 [Network Architecture Principles]

As more links are added to a network, the control plane slows down due to more data to process. As redundancy increases, MTTR also increases. Which risk increases along with the higher MTTR?

A. Management visibility

B. Slower data plane convergence

C. Overlapping outages

D. Topology change detection

Answer: C

????   Explanation:

C: As MTTR (Mean Time to Repair) increases due to complex topologies and control plane delays, the likelihood of experiencing overlapping outages (i.e., a second failure occurring before the first is resolved) also increases. This can cascade into a wider outage.

Other options:

A: Management visibility isn’t directly affected by MTTR.

B: Data plane convergence is generally fast and not as affected as control plane convergence.

D: Topology changes may still be detected quickly, but the reaction time (recovery) is delayed.

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????   QUESTION NO: 346 [Security, Automation, and Policy Integration in Design]

Which layer of the SDN architecture orchestrates how applications receive available network resources?

A. Orchestration layer

B. Southbound API

C. Northbound API

D. Control layer

Answer: A

????   Explanation:

A: The orchestration layer manages global resource allocation, service policies, and end-to-end workflows. It ensures that applications receive the necessary resources through coordination between the control and application layers.

Other options:

B: Southbound APIs connect the control layer to the infrastructure layer.

C: Northbound APIs connect the control layer to applications but don’t handle orchestration.

????  QUESTION NO: 347 [Security, Automation, and Policy Integration in Design]

Company XYZ wants to detect and block known attacks by inspecting every forwarded packet with minimal performance impact. What is the recommended design?

A. Deploy an IPS behind the firewall in promiscuous mode

B. Deploy an IPS in front of the firewall in promiscuous mode

C. Deploy an IPS behind the firewall in in-line mode

D. Deploy an IPS in front of the firewall in in-line mode

Answer: C

????  Explanation:

C: Deploying the IPS behind the firewall in in-line mode ensures that only filtered and relevant traffic is inspected, minimizing performance impact while still allowing the IPS to block malicious packets. Inline mode allows for active blocking based on signature detection.

A and B: Promiscuous mode only detects but does not block traffic.

D: Placing IPS in front of the firewall increases the processing load by exposing it to all traffic, including unwanted or already-blocked connections.

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????  QUESTION NO: 348 [Technology Comparisons and Use Cases]

In an SDN architecture, what is present on the switches but not on the centralized controller?

A. Control plane functions

B. A southbound interface

C. Data plane functions

D. A northbound interface

Answer: C

????  Explanation:

C: In SDN, switches retain the data plane functionality—they forward packets based on flow rules received from the controller.

A: Control plane functions are moved to the centralized controller in SDN.

B: Southbound interfaces are present on both controllers and switches for communication.

D: Northbound interfaces exist on controllers to interact with applications—not switches.

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????  QUESTION NO: 349 [Technology Comparisons and Use Cases]

What is a connection service that provides direct connectivity to a cloud provider from a data center?

A. Cloud OnRamp

B. Cloud Gateway

C. Cloud Direct Connect

D. Carrier-neutral facility

Answer: C

????  Explanation:

C: Cloud Direct Connect (or equivalent, e.g., AWS Direct Connect, Azure ExpressRoute) provides private, low-latency connectivity between on-prem data centers and public cloud providers.

A: Cloud OnRamp is part of Cisco SD-WAN solutions that optimize SaaS and IaaS access.

B: Cloud Gateway typically refers to a device or service that connects on-prem to cloud, but not necessarily direct, private circuits.

D: Carrier-neutral facilities are physical data centers used for interconnection but not themselves the service.

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????  QUESTION NO: 350 [Scenario-Based Design Strategy Guidance]

A customer is designing a network to support video applications with centralized and distributed deployments. The team has reviewed bandwidth, cost, and usage patterns. What additional key information is missing?

A. Video traffic jitter and delay

B. Type of video resources

C. Transport protocol and traffic engineering

D. Network management and monitoring

Answer: B

????  Explanation:

B: The type of video resources (e.g., MCUs, call agents, conferencing servers) significantly affects whether a centralized or distributed deployment is more efficient. This decision impacts call setup, bridging, and media flow.

A: While jitter/delay are QoS concerns, they don’t dictate the resource allocation model by themselves.

C and D: Important for operations and engineering but not the missing business-critical input for resource placement.

A (BGP PIC — Prefix Independent Convergence) enables BGP to rapidly converge during link or node failures by pre-installing backup forwarding paths in the FIB.

BGP PIC minimizes traffic loss during failover, improving resiliency in both edge and core environments, and is a key recommendation for scalable and high-availability BGP design in CCDE v3.1.

Why other options are incorrect:

B: BGP-EVPN is used for L2VPN services, not for fast convergence.

C: BGP FlowSpec is used for DDoS mitigation and traffic filtering.

D: BGP-LS (Link-State) provides topology distribution for controllers, not convergence.