Selected 400-007 CCDE Questions Answers

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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A (PPDIOO - Prepare, Plan, Design, Implement, Operate, Optimize):PPDIOO is Cisco’s structured lifecycle methodology designed specifically for network design, deployment, and management. It ensures continuous improvement, iterative design, and aligns technical efforts with business goals throughout the entire network lifecycle.

Other options explained:

B: Waterfall is a generic software development methodology.

C: Spiral emphasizes iterative risk management for software development.

D: V model applies primarily to software verification and validation.

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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B (MPLS over BGP over mGRE):This design allows enterprises to run MPLS VPNs across their own infrastructure (Overlay VPN) while using MP-BGP for control plane distribution of VPNv4 routes. The mGRE tunnel structure allows scalability as branches grow, while MPLS VPN labels ensure traffic separation.

Other options explained:

A: EIGRP OTT is not scalable for large VPN deployments.

C: DMVPN per VRF becomes complex with high scale growth.

D: Point-to-point GRE per VRF lacks scalability for 60+ sites.