Pass the Cisco CCDE v3.0 400-007 Questions and answers with CertsForce

????  Comprehensive Explanation:

A: In hybrid WAN designs where routing domains are gradually migrating from OSPF to BGP, particularly with overlapping domains or redistribution points, loops can occur if the same routes are seen via multiple protocols (e.g., BGP and OSPF). Implementing route filtering on the OSPF backbone prevents it from learning and advertising spoke routes that it also receives via BGP—eliminating the loop scenario.

B: Advertising a low administrative distance (AD) for transit traffic does not prevent loops and may worsen convergence or cause routing inconsistency.

C: Summarizing OSPF routes may reduce the routing table size, but it does not solve the loop issue caused by dual protocol redistribution unless filtering is applied.

D: Redistributing EIGRP routes into BGP with a low cost might cause preference toward one path but does not address the loop risk between the hybrid segments (OSPF and BGP).

This is a classic use case for route filtering in dual-protocol or dual-backbone migrations, where ensuring consistent path selection and loop prevention is essential.

????  QUESTION NO: 356 [Network Architecture Principles]

A network becomes unintentionally segmented when remote sites connect to HQ only via the public Internet. Which option helps de-segment the network?

A. Build virtual networks that pass over the network

B. Mark traffic for special handling through quality of service

C. Configure little to no control data plane policy

D. Block specific sources from reaching specific destinations

Answer: A

????  Explanation:

A: Virtual networks (e.g., VPNs, tunnels) create secure, logical overlays across segmented physical infrastructure such as the public Internet, effectively re-integrating remote sites into the corporate network. This re-establishes end-to-end connectivity and consistent routing/security policies.

Other options:

B: QoS does not address segmentation or connectivity.

C: Lax control-plane policies do not restore logical network integration and may increase security risk.

D: Blocking traffic further limits connectivity and exacerbates segmentation.

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????  QUESTION NO: 357 [Protocol Design Implications]

You want to add 900 VLANs to an existing 90 in a data center. What are two spanning tree concerns to consider?

A. STP is increased by a factor of 10 convergence time

B. To add 990 VLANs to the switching hardware, reserved VLANs require using extended VLAN

C. The diameter of the STP topology is increased

D. The PVST+ increases CPU utilization

E. BPDU does not support 990 VLANs

Answer: B, D

????  Explanation:

B: Cisco switches reserve certain VLAN IDs. VLANs beyond 1005 are considered extended VLANs and may require special configuration (e.g., VTP transparent mode).

D: Each VLAN with PVST+ has its own instance of STP. Adding 900 more VLANs significantly increases the STP processing overhead on the switch’s control plane and CPU.

Other options:

A: STP convergence time is more dependent on topology than VLAN count.

C: STP diameter is unrelated to the number of VLANs—it ' s a function of hops in the topology.

E: BPDU handling is VLAN-aware under PVST+; there’s no direct per-BPDU VLAN limitation.

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????  QUESTION NO: 358 [Business-Driven Design Approaches]

Which strategic requirement pushes decision-makers toward IaaS over SaaS or PaaS?

A. Selling products and services globally 24/7

B. Integration with partner or vendor supply chains

C. Control over the underlying infrastructure

D. Speed-to-market is more important for an initiative

Answer: C

????  Explanation:

C: IaaS (Infrastructure as a Service) provides the greatest control over compute, storage, and network resources. Organizations that require fine-grained control (e.g., compliance, tuning, OS/hardware) will prefer IaaS over SaaS or PaaS.

Other options:

A and B: These may be satisfied by SaaS or PaaS depending on architecture.

D: PaaS and SaaS often offer faster time-to-market than IaaS.

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????  QUESTION NO: 359 [Security, Automation, and Policy Integration in Design]

To meet PCI-DSS requirements under Strong Access Control Measures, which two conditions must be met?

A. Assign a unique ID to each person with computer access

B. Restrict access to cardholder data on a need-to-know basis

C. Encrypt transmission of cardholder data across open or public networks

D. Each location must require validating PCI compliance if business has multiple locations

E. Protect stored cardholder data

Answer: A, B

????  Explanation:

A: PCI-DSS Requirement 8 mandates that each user have a unique ID to track and control access.

B: PCI-DSS Requirement 7 enforces least privilege—only users with a legitimate business need should access cardholder data.

Other options:

C: This relates to transmission security, not access control.

D: PCI compliance requirements may be managed centrally depending on structure.

E: Protecting stored data is critical but falls under data protection, not access control.

????  QUESTION NO: 360 [Business-Driven Design Approaches / Project Methodologies]

Which project management methodology is characterized by having low client involvement?

A. Traditional project management

B. LEAN project management

C. Kanban project management

D. Agile project management

Answer: A

????  Explanation:

A: Traditional project management (often referred to as the Waterfall model) involves a fixed sequence of phases—planning, design, execution, and delivery. Client involvement is typically high at the beginning (requirements gathering) and low during implementation.

Other options:

B, C, and D (LEAN, Kanban, Agile): These emphasize continuous feedback, flexibility, and frequent customer interaction throughout the project lifecycle. Agile in particular encourages constant client collaboration via sprints and reviews.

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????  QUESTION NO: 361 [Protocol Design Implications / High Availability]

Two routers (R1 and R2) run OSPF and have registered with BFD in asynchronous mode with the echo function enabled. Which two actions occur with the echo function? (Choose two)

A. BFD control packets are sent at a slower pace because the echo function is enabled

B. BFD echo packets are sent from forwarding engines along the Layer 2 path to perform detection

C. BFD control packets are sent at a higher pace because the echo function is enabled

D. Only BFD control packets are sent from forwarding engines along the Layer 2 path to perform detection

E. BFD sessions at either end actively participate in the forwarding of echo packets

Answer: B, E

????  Explanation:

B: BFD echo packets are looped back by the peer and sent through the data plane (forwarding engine) over the actual Layer 2 path. This ensures the link is not only up logically but physically functional.

E: Both ends of the BFD session (R1 and R2) participate in sending/receiving and forwarding echo packets, validating bidirectional liveliness.

Other options:

A: Echo packets are independent of control packets. Echo may offload failure detection to data plane but does not reduce control packet frequency.

C: Control packet rate is not increased by echo function.

D: Both control and echo packets play roles; it’s not " only control packets " or “only echo packets” used in detection.

The scenario requires controlling how AS 111 sends its outbound traffic (egress traffic). BGP policy control for outbound traffic is best handled via manipulating the BGP Local Preference attribute, as:

Local Preference (LocalPref) influences path selection for outbound traffic by setting a preference for one path over another.

It is evaluated within the AS and does not require coordination with external autonomous systems.

LocalPref changes are fully contained inside AS 111 and satisfy the requirement to only affect AS 111.

A higher Local Preference value is preferred, thus you set higher values for routes learned via AS 100.

Why other options are incorrect:

A (community): Typically influences inbound traffic or interacts with upstream providers.

B (MED): Influences inbound traffic for external neighbors, not outbound.

D (AS Path): Also primarily influences inbound traffic selection by remote ASes.

B (Minimize operational costs): A common business goal to reduce long-term operating expenses.

E (Reduce complexity): Simplifying designs reduces operational overhead, risk, and failure domains.

Why other options are incorrect:

A: Resiliency is a design goal, but not a business objective itself.

C: Endpoint posture is a technical security feature.

D: Faster obsolescence contradicts business optimization.

In a full-mesh iBGP design, every router must establish and maintain a BGP session with every other router. As the number of routers increases, the number of BGP sessions and the amount of BGP processing increases exponentially. This leads to high CPU utilization, especially in devices with limited processing capabilities, such as distribution routers.

Themost cost-effectiveandscalablesolution in this scenario is toimplement route reflectors (RRs)on the two core routers. Route reflectors significantly reduce the number of iBGP peerings required, eliminating the full mesh requirement by allowing the distribution routers (RR clients) to establish a single iBGP session with the route reflector. The route reflector handles route advertisement to other RR clients, thereby reducing overhead on the distribution routers.

This solution adheres to CCDE v3.1 design principles for:

Optimizing control plane scalability

Reducing unnecessary CPU load from control protocols

Ensuring a maintainable and scalable enterprise BGP deployment

Why the other options are incorrect:

BandD(Increasing memory): Addresses only hardware capacity without solving the root cause (BGP scaling issue).

C(Using eBGP): Misaligned with enterprise internal network design; eBGP adds complexity in route policy and administrative boundaries.

E(Increasing bandwidth): Bandwidth does not alleviate CPU overhead caused by BGP processing.

Implementing route reflectors aligns with both scalability and cost-efficiency goals as prescribed in the CCDE v3.1 methodology.

EIGRP’s convergence time is heavily impacted by the size of the query domain — the group of routers involved when a route goes into active state. The larger the query domain, the longer the convergence. Summarization naturally bounds query propagation because routers receiving a summary have no knowledge of individual prefixes beyond that summary, preventing them from being queried about specifics they don’t track.

This design technique is emphasized in CCDE v3.1 because:

Summarization reduces the query scope.

Faster convergence happens as fewer routers process queries.

Hierarchical design is enabled for stability and scalability.

Why other options are incorrect:

A: Distribute lists filter prefixes but don ' t reduce query propagation.

B and C: Triangulated or squared physical topology doesn’t control protocol-level query scope.

E: Default routes may help limited routing domains but don’t optimize EIGRP convergence specifically.

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D (Data confidentiality rules): The most critical factor in cloud service placement is data confidentiality and compliance with regulatory requirements. Certain data may not legally or contractually be permitted to leave specific geographic or organizational boundaries, directly influencing whether a public, private, hybrid, or on-premise deployment is used.

Other options explained:

A: Replication cost is important but secondary to legal and regulatory compliance.

B: Application structure affects architecture but doesn ' t override confidentiality restrictions.

C: Implementation time is a project management concern, not a service placement driver.

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The distribution layer serves as the boundary between the access and core layers in the three-tier hierarchical design. It plays a crucial role in providing policy enforcement, control, and boundary functions, including:

QoS classification and marking (C): The distribution layer serves as the boundary for Quality of Service policies. It marks and classifies traffic as it moves from access to core layers, ensuring proper QoS treatment in the core.

Redundancy and load balancing (E): The distribution layer provides link redundancy (e.g., dual-homing access layer switches) and performs load balancing to optimize path selection toward the core.

Other options explained:

A (Fast transport): Typically associated with the core layer, which focuses on high-speed forwarding.

B (Reliability): While reliability is a network-wide goal, it’s not a primary function of the distribution layer specifically.

D (Fault isolation): While partial fault containment occurs, primary fault isolation happens at the access layer.

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C (SPF hold time): Controls the minimum amount of time between Shortest Path First (SPF) recalculations in link-state protocols like OSPF and IS-IS. This mechanism prevents frequent SPF runs due to rapid or transient topology changes, providing stability.

Other options explained:

A: Transmit delay affects LSA propagation but not routing protocol recalculation timing.

B: Throttle timers are related but primarily control LSA generation intervals.

D: Interface dampening suppresses flapping i

Control plane hardening is a critical aspect of securing infrastructure devices. Recommended measures include:

A. Routing protocol authentication: Prevents unauthorized devices from injecting false routes by requiring secure key-based authentication (e.g., MD5 or SHA for OSPF/BGP).

B. SNMPv3: Provides secure management through authentication and encryption, preventing interception or modification of SNMP traffic.

C. Control Plane Policing (CoPP): Enforces rate limits and filtering for traffic directed to the device ' s CPU, protecting against DoS and control plane overloads.

Why other options are incorrect:

D. Redundant AAA servers support authentication resilience but are more about access control than direct control plane protection.

E. Warning banners are a legal and administrative best practice, not a technical control plane defense.

F. Enabling unused services is the opposite of best practices and increases the attack surface.

These control-plane protections are emphasized in CCDE v3.1 design guidance for resilient and secure infrastructure designs.