Free Cisco 400-007 Practice Exam with Questions & Answers | Set: 12

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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When both networks use overlapping private IP addresses, a single Cisco IOS NAT router can handle bidirectional NAT with dynamic NAT (overload). However, it requires careful configuration using:

Two distinct NAT pools: One for traffic sourced from side A, and one for traffic sourced from side B.

ip nat inside source and ip nat outside source commands with the overload keyword.

Interfaces must be properly defined with ip nat inside and ip nat outside to reflect traffic directionality.

Option D is correct because it explicitly reflects the requirement to use two different NAT pools for overload in both directions, which ensures proper address translation and session tracking.

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This scenario describes a centralized control mechanism where:

The SDN controller learns the network topology using BGP Link-State (BGP-LS).

The controller installs control-plane policies using protocols like PCEP or BGP.

Policies are pushed centrally and result in new RIB entries at the routers.

This is the hallmark of a centralized SDN architecture:

The controller has a global view and decision-making logic.

Routers remain relatively simple in the control plane and act on instructions.

This aligns with CCDE v3.1 under the “Technology Comparisons and Use Cases” topic, where SDN models are compared:

Centralized SDN (controller-driven)

Distributed SDN (traditional)

Hybrid (a blend of both, which is not represented here)

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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.

A (EoMPLS): Ethernet over MPLS can operate at Layer 2, and MACsec can encrypt traffic before entering the MPLS core.

E (KVPLS): Supports MACsec encryption for Layer 2 DCI services over VPLS solutions.

Why other options are incorrect:

B: MPLS L3 VPN operates at Layer 3, not suitable for MACsec (L2 encryption).

C: DMVPN uses IPsec, not MACsec.

D: GET VPN uses IPsec for L3 traffic encryption.

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D (Deploy SD-WAN edge routers in data center, then controllers, then branches):This allows the SD-WAN fabric to be built and stabilized centrally first, then controllers are brought online for policy orchestration, and finally, branch migrations happen gradually without impacting existing traffic paths.

Other options explained:

A/B/C: These approaches risk service disruption or poor controller orchestration readiness during branch migrations.

PBR overrides the normal routing table behavior, potentially leading to microloops during reconvergence because forwarding decisions are based on policies rather than updated routing tables.

During fast topology changes, PBR decisions may not adapt as quickly as dynamic routing protocols, causing brief routing inconsistencies.

Why other options are incorrect:

A: PBR can add complexity but does not inherently limit scalability.

C/D: PBR does not directly affect convergence speed but can introduce inconsistency.