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

B (Automation spans multiple vendors and services):Automation tools can handle provisioning, configuration, monitoring, and integration across heterogeneous vendor networks.

D (Provisioning services = automation):Routine tasks like service provisioning, device onboarding, or configuration are handled by automation systems to reduce operational workload.

Other options explained:

A: Automation can absolutely include policy enforcement if integrated properly.

C: Orchestration governs higher-level workflows across multiple domains and uses APIs but is not limited to basic automation tasks.

E: Orchestration coordinates complex workflows, not just single low-level tasks.

Public cloud offers scalability, flexibility, and consumption-based pricing, which directly reduces capital expenditures (CAPEX) and minimizes operational burden (less IT staff needed for infrastructure maintenance).

Public cloud eliminates upfront hardware investments and shifts cost to predictable operational expenses.

Public cloud providers handle hardware maintenance, upgrades, and scalability, making it highly cost-effective for government agencies with fluctuating workloads.

Why other options are incorrect:

A: On-premises increases CAPEX and requires significant IT staff.

B: Private cloud reduces some OpEx but still requires infrastructure management and higher CAPEX.

D: Hybrid cloud increases complexity and operational costs.

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Private cloud architecture provides:

On-demand provisioning and decoupling from hardware

Security controls under enterprise ownership

Strong isolation — comparable to an air-gapped model if fully controlled on-premises or in a dedicated hosted environment

While public or hybrid clouds offer flexibility, they cannot guarantee security parity with air-gapped systems unless significant additional controls are implemented. Private cloud supports containerized architectures and modern DevOps pipelines, while keeping the data plane within enterprise boundaries.

This aligns with CCDE’s cloud design principles — balancing modernization goals with strict compliance and cybersecurity mandates.

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BFD (Bidirectional Forwarding Detection) provides rapid failure detection independent of OSPF’s native hello/dead timers.

BFD operates at subsecond intervals (as low as 50ms), detecting link failures almost immediately, allowing OSPF to react instantly upon failure detection.

BFD complements OSPF and significantly improves convergence time without compromising OSPF’s stability.

Why other options are incorrect:

A: STP is irrelevant for Layer 3 routing failures.

B: Fate sharing describes failure domains, not detection mechanisms.

C: OSPF LFA provides fast reroute after failure detection but doesn’t accelerate detection itself.

E: Flex links are used in Layer 2 switching, not for OSPF-based WAN failover.

C (Layer 2 switches unaffected):IPv6 operates at Layer 3, so pure Layer 2 switches forward frames without needing IPv6 awareness. As long as switches can transparently forward Ethernet frames, IPv6 functionality will be preserved, minimizing unnecessary hardware upgrades.

Other options explained:

A/B/D: These unnecessarily increase cost and complexity for basic Layer 2 functionality where IPv6 awareness is not mandatory.

Comprehensive and Detailed Explanation:

CAPEX (Capital Expenditures) focuses on up-front hardware investments, like routers, switches, and appliances.

A: Scalability directly impacts CAPEX—network designs that require fewer or more scalable hardware components reduce capital investment costs.

B and D are more influenced by OPEX (operational expenditures).

C (complexity) is a broader design challenge, not directly tied to CAPEX.

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Let’s calculate the total cost for each solution based on the most likely maximum duration (20 + 10 = 30 months) to ensure conservative, flexible planning.

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DWDM over dark fiber:

CAPEX = $200,000

OPEX (annual): $100,000⇒for 30 months = (2.5 × $100,000) = $250,000

Installation fee = $30,000

Total = $200,000 + $250,000 + $30,000 = $480,000

CWDM over dark fiber:

CAPEX = $150,000

OPEX (annual): $100,000⇒for 30 months = (2.5 × $100,000) = $250,000

Installation fee = $25,000

Total = $150,000 + $250,000 + $25,000 = $425,000

MPLS wires only:

CAPEX = $50,000

OPEX (annual): $180,000⇒for 30 months = (2.5 × $180,000) = $450,000

Installation fee = $5,000

Total = $50,000 + $450,000 + $5,000 = $505,000

Metro Ethernet:

CAPEX = $65,000

OPEX (annual): $100,000⇒for 30 months = (2.5 × $100,000) = $250,000

Installation fee = $5,000

Total = $65,000 + $250,000 + $5,000 = $320,000

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Analysis:

Metro Ethernet has the lowest overall cost at $320,000 and provides sufficient flexibility for workload migration since "all connectivity options meet technical requirements."

Metro Ethernet is typically more flexible than DWDM/CWDM for temporary or dynamic migration projects because it does not require optical expertise or complex dark fiber management.

MPLS is more expensive here and less flexible for large-scale Layer 2 migrations.

CWDM/DWDM are suitable for permanent solutions where long-term investment is justified, but not optimal here due to cost.

Therefore, best ROI and flexibility: Metro Ethernet

Final correct answer: D

Performance management is the FCAPS function responsible for collecting statistics, monitoring utilization, identifying performance degradation, and optimizing network responsiveness.

It ensures that the network maintains SLA targets.

Why other options are incorrect:

A: Fault management detects and responds to failures.

B: Accounting tracks resource usage.

D: Security handles access and policy enforcement.

Software-defined network segmentation is a core element of secure cloud architecture models.

It isolates workloads, minimizes blast radius, and enforces east-west security controls in dynamic multi-tenant environments.

Why other options are less appropriate:

A: This is a principle of least privilege (IAM) but not a cloud architecture characteristic.

B: Dedicated workstations are endpoint measures, not architecture-level.

C: MFA protects identity but does not define architecture segmentation.

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Mutual redistribution between different routing protocols can cause routing loops and suboptimal routing due to:

Route feedback loops (routes being re-imported back into the originating protocol).

Inconsistent administrative distances (AD) leading to selection of suboptimal paths.

Two key mechanisms avoid these issues:

A. Administrative Distance (AD) manipulation: Ensures that one protocol is consistently preferred over the other when duplicate routes exist.

C. Route tagging: Assigns tags to redistributed routes to identify the source of the route and prevent re-importation (looping) into the originating protocol.

These methods align with CCDE v3.1 principles for multi-protocol control plane design and stability.

Why other options are incorrect:

B & F: Matching routes or process IDs do not directly prevent loops or suboptimal routing.

D is a duplicate of C.

E: Filtering helps but is reactive, not a comprehensive prevention mechanism.

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