400-007 Dumps with Practice Exam Questions Answers

A (VXLAN offers native loop avoidance): VXLAN uses Layer 3 underlay with encapsulation, inherently avoiding Layer 2 loops common in traditional Layer 2 fabrics.

Why other options are incorrect:

B: Storm control mitigates broadcast storms but doesn ' t prevent loops.

C: vPC+ helps but doesn’t replace VXLAN ' s loop-free architecture.

D: BPDU Guard helps protect edge ports, but loop prevention in VXLAN is primarily handled by its Layer 3 foundation.

In the topology shown, the 10.10.0.0/16 network is redistributed into two different OSPF processes—OSPF 1 and OSPF 2—from router R3. The redistribution uses the external route types:

Into OSPF 1 as an E1 route with a metric of 100

Into OSPF 2 as an E2 route with a metric of 100

When redistribution occurs in OSPF, two types of external routes can be injected:

Type E1: Adds the internal OSPF cost to the external cost (total path cost = external metric + internal OSPF path)

Type E2: Considers only the external cost and ignores internal path cost (default behavior)

In this case:

The path via R2–R3 (E1) includes both the external cost and the internal cost from R1 to R2 to R3. That is: 10 (R1–R2) + 10 (R2–R3) + 100 (external) = 120.

The path via R4–R5–R3 (E2) will show a constant metric of 100 regardless of the internal OSPF path (10 + 10 = ignored).

So when the link between R2 and R3 fails, the path R1–R4–R5–R3 (E2 route with constant metric 100) becomes the preferred route.

However, when the link between R2 and R3 is restored, the E1 route will be recalculated as:

Internal cost (R1–R2–R3) = 10 + 10 = 20

External metric = 100

Total = 120

OSPF always prefers E1 routes over E2 routes when both are available, even if the E2 route appears to have a better metric. This is because E1 routes provide more accurate end-to-end cost calculation.

Therefore, upon restoration, the routing table reverts to the E1 route via R1–R2–R3.

This behavior is aligned with OSPF protocol standards and is emphasized in CCDE v3.1 under the “Protocol Design Implications” domain, which focuses on redistribution behaviors, route-type preferences, and convergence consistency in multi-domain IGP designs.

A: On most hardware platforms, control plane protection is implemented in hardware to safeguard CPU resources from overload due to excessive control traffic.

E: Control plane policing must be carefully sized to allow sufficient protocol traffic (OSPF, BGP, etc.) during normal and convergence periods to ensure stability.

Why other options are incorrect:

B: Policing should be applied universally, not just on external interfaces.

C: False alarms are operational issues but not design considerations.

D: Control plane policers are applied after forwarding decisions for traffic destined to the router CPU.

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B (OSPF Type 1 external):Type 1 external routes include both the external cost (from redistribution) and the internal OSPF cost to the ASBR. This ensures accurate end-to-end metric calculation across domains.

Other options explained:

A: Type 2 external ignores internal OSPF cost, potentially creating suboptimal routing.

C/D: EIGRP doesn’t use OSPF metric types; redistribution into EIGRP uses EIGRP metrics.

A (Posture assessment with remediation VLAN):Posture assessment checks endpoint compliance (such as AV definitions). Non-compliant devices are placed into a remediation VLAN where they can update before regaining normal network access.

Other options explained:

B: SGTs provide segmentation but are not posture-specific.

C: dACLs with SGTs handle policy enforcement, but posture control is required for AV compliance.

D: Quarantine VLAN isolates devices but doesn’t automate remediation.