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

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.

C (Synchronous replication over Metro Ethernet) provides real-time replication with zero data loss (RPO = 0) and minimal recovery time (RTO ≈ 0).

Metro Ethernet offers low-latency, high-bandwidth, and deterministic connectivity between closely located data centers, ideal for synchronous replication.

Why other options are incorrect:

A & D: Asynchronous replication cannot guarantee zero RPO/RTO.

B: MPLS introduces variable latency unsuitable for synchronous replication.

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Bidirectional Forwarding Detection (BFD) provides fast failure detection independent of routing protocols. It can be integrated with multiple protocols to accelerate convergence:

A: IS-IS supports BFD for fast hello processing.

B: BFD can track static routes via routing tracking features.

D: EIGRP supports BFD for link failure detection.

E: BGP supports BFD for rapid session teardown.

Why option C is incorrect:

C: RIP does not natively support BFD integration.

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D (High latency):In three-tier architectures, east-west traffic between different pods (access domains) must traverse additional layers (distribution and core), introducing extra hops and thus adding latency. This inefficiency is one reason why spine-leaf architectures are favored for modern data centers.

Other options explained:

A: Bandwidth is less of a concern with high-speed core links.

B: Security is not directly affected by east-west traversal in this architecture.

C: Scalability is limited, but the primary issue for east-west traffic is latency.

CPPr (Control Plane Protection) allows classification and policing of traffic destined for the control plane at a more granular level than CoPP.

It protects the router from control plane attacks such as reconnaissance scans and DoS targeting interfaces and sub-interfaces.

Why other options are incorrect:

A: MPP protects management plane access, not data/control plane protection.

C: CoPP offers global control plane policing but lacks CPPr’s granularity.

D: DPP is not a standard Cisco security mechanism.

Comprehensive and Detailed Explanation:

To reduce oscillation and improve resiliency:

D: Increasing unequal-cost multipath (UCMP) paths allows the routing protocol to load-share over more than one path, preventing traffic congestion from oscillating between nodes.

E: Dual links to each site improve bandwidth and failover options, reducing reliance on overloaded peers.

Other options:

A: Increasing redundant paths may worsen convergence complexity and doesn't solve oscillation.

B: Removing inter-spoke links reduces redundancy.

C: Increasing convergence timers delays recovery and stability.

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The question describes a network that requires virtualization at both control and data plane levels using VLANs and VRFs. This architecture aligns with:

Path isolation (A): Achieved using VRFs and VLANs, ensuring traffic separation at Layer 2 and Layer 3 across the entire network.

Group virtualization (C): Refers to grouping users or resources (such as departments or tenants) into isolated segments that remain logically separated throughout the campus fabric.

Other options explained:

B (Session isolation): More aligned with application or session-layer security, not data/control plane virtualization.

D (Services virtualization): Typically related to virtualizing network services (firewalls, load balancers).

E (Edge isolation): Not a standard design term in CCDE.

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B (OTV — Overlay Transport Virtualization): Allows Layer 2 extension across data centers while maintaining fault isolation by not extending STP across the WAN. Control plane handles MAC learning, which provides stability and loop avoidance between data centers.

Why other options are incorrect:

A: FabricPath is mainly for intra-data center Layer 2 fabric.

C: Advanced VPLS extends Layer 2 but carries STP across the WAN.

D: LISP operates at Layer 3, not for Layer 2 extension.

E: TRILL also focuses on intra-DC Layer 2 but not DCI fault isolation.

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D (GRE Key and Sequence Number extensions):The GRE Key field provides session identification for distinguishing between multiple GRE tunnels. The Sequence Number extension allows endpoints to track packet ordering and detect lost or out-of-order packets, enhancing reliability at the tunnel level if required.

Other options explained:

A: Protocol Type identifies payload type; Checksum detects errors but doesn't provide sequencing.

B: GRE Version and Reserved0 fields are not used for session or sequencing.

C: GRE does support optional extensions, contrary to this statement.

DUMPS (Designated Unified Multiprotocol Redistribution Strategy) using single-point redistribution with route tagging ensures scalable, loop-free redistribution.

Route tags prevent redistributed routes from being re-advertised into the originating protocol, avoiding routing loops even with multiple paths.

Single-point redistribution simplifies operational complexity compared to multipoint redistribution.

Why other options are incorrect:

A, B, D: ACLs are not scalable for filtering redistributed routes in large networks. Tags provide better control.