400-007 Cisco Certified Design Expert (CCDE v3.1) Free Practice Exam Questions (2026 Updated)

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.

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.

When unmanaged switches are connected to access ports, there ' s a risk that they may start participating in Spanning Tree Protocol (STP) or introduce loops. BPDU Guard is the most effective mechanism to mitigate this risk:

BPDU Guard disables a port immediately upon receiving any BPDU, ensuring that only end hosts (non-switch devices) are connected to access ports.

This protects the stability of the STP topology by preventing accidental or malicious introduction of switches into the Layer 2 domain.

Other options explained:

A (PortFast): Accelerates port transition to forwarding state but does not protect against loops caused by BPDUs.

B (UDLD): Detects unidirectional physical link failures but not STP participation.

C (Root guard): Prevents the connected device from becoming a root bridge but still allows BPDUs.

—

When multiple virtualized network zones (such as VRFs, virtual firewalls, or logical partitions) are consolidated onto a single physical device, the primary concern is:

A (Fate sharing): A single hardware failure, software crash, or resource exhaustion event could simultaneously impact all virtualized zones, creating a shared risk across multiple otherwise isolated services.

Other options explained:

B: CPU resource allocation can be controlled via resource management but is not the primary risk.

C: Congestion control is typically a traffic engineering issue, not a virtualization risk.

D: Security isolation can be maintained through proper virtualization boundaries.

E: Bandwidth can be managed through QoS and resource allocation.

—

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.

B (Strategic planning): Long-term business-aligned decisions that shape future infrastructure needs.

D (Tactical planning): Short-to-mid-term activities that adjust design based on evolving operational realities, constraints, and priorities.

Why other options are incorrect:

A and E: While cost and business optimization are goals, they are not defined planning approaches.

C: Modular is a design methodology, not a planning approach.

—

B (Encapsulation at source and destination):Overlay networks encapsulate payloads inside another protocol (e.g. VXLAN, GRE, MPLS), adding headers that enable separation from the underlay network while introducing minor overhead due to encapsulation.

Other options explained:

A: Describes underlay behavior.

C: Overlay encapsulation occurs independently of L3/L4 reliability.

D: NAT or VRF are isolation mechanisms but not how overlays function.

A (Fault management):Covers detection, isolation, notification, and resolution of network issues to ensure minimal downtime and service disruptions, directly aligning with the design goal of preventing and mitigating outages.

Other options explained:

B: Performance management monitors resource usage but doesn’t directly handle faults.

C: Security management handles authorization, authentication, and protection.

D: Accounting management deals with usage tracking for billing and auditing.

B (Cloud OnRamp for IaaS):This allows certain applications to have direct optimized access to public cloud resources while other enterprise traffic remains centralized. OnRamp for IaaS provides dynamic path selection and policy control based on application behavior and performance.

Other options explained:

A: MPLS L3VPN does not offer cloud-optimized direct access.

C: SaaS OnRamp is for SaaS applications, not IaaS workloads.

D: Direct Connect links to the cloud but lacks policy-driven traffic engineering.

Cisco SD-WAN Cloud OnRamp SaaS optimizes cloud application performance by dynamically measuring SaaS application paths from multiple branch edges toward the Microsoft 365 cloud.

It automatically selects the best-performing path, continuously monitors SLA metrics (latency, loss, jitter), and dynamically reroutes based on real-time performance.

This directly addresses SaaS resiliency across multiple ISPs with minimal manual intervention and is aligned with CCDE v3.1 SD-WAN design methodologies for SaaS optimization.

Why other options are incorrect:

A: Cloud OnRamp gateway is for IaaS optimization (AWS, Azure), not SaaS.

B: Cloud OnRamp SWG (Secure Web Gateway) is for internet-bound security inspection, not SaaS path optimization.

C: " Cloud OnRamp " alone is too general; SaaS is the specific solution for this SaaS use case.

D (Aggregation layer termination):The aggregation layer is the ideal demarcation for Layer 2 interconnects because it maintains clear boundaries between Layer 2 and Layer 3 domains, simplifies STP and routing design, and preserves hierarchical scalability.

Other options explained:

A: Core should remain strictly Layer 3 for scalability and stability.

B: Access-layer interconnection introduces STP complexity.

C: Security concerns are handled via policy, not termination layer

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.

A (SD-WAN):SDN principles are widely adopted in wide area networks for dynamic path selection, centralized control, and policy enforcement.

B (Mobile networks):5G and modern mobile networks leverage SDN/NFV architectures to virtualize core services and optimize resource utilization.

Other options explained:

C: Metro networks adopt SDN, but WAN and mobile are more common mainstream use cases.

D/E: Application and control network are not direct SDN network types.

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.

During massive BGP update events (such as after a topology change), a route reflector may struggle processing both BGP updates and the resulting TCP acknowledgments required for reliable BGP session communication.

Increasing the hold queue size allows the router to buffer more packets waiting for processing (including TCP acknowledgments), helping the router handle bursts of BGP updates without dropping TCP segments or tearing down sessions.

This queue tuning is a well-known scalability optimization in CCDE v3.1 when designing route reflector clusters handling large-scale control plane updates.

Why other options are incorrect:

B and C: Adjusting buffer sizes does not directly address TCP acknowledgment backlog.

D: Keepalive timers control session liveliness, not update processing.

—