400-007 Cisco Certified Design Expert (CCDE v3.1) Free Practice Exam Questions (2025 Updated)

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.

GLOP addressing is defined in RFC 2770. It assigns globally unique multicast addresses based on an organization's ASN by mapping the 16-bit ASN into the middle two octets of the 233.0.0.0/8 address space.

233.0.0.0/8 is specifically reserved for GLOP addressing.

The uniqueness of the address is derived from the assigned ASN.

Why other options are incorrect:

A: 232.0.0.0/8 is SSM address space.

C: 239.0.0.0/8 is for administratively scoped multicast.

D: 224.0.0.0/24 is reserved for local multicast (link-local scope).

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Cisco NFVi (Network Function Virtualization Infrastructure) solutions integrate with Red Hat’s virtualization stack using:

C. Cisco Nexus switches: Provide data center network fabric.

D. Cisco UCS: Provides the compute platform for NFV workloads.

F. Cisco Virtual Network Functions: The software-based network functions running on NFVi (e.g. virtual routers, firewalls, etc.).

Why other options are incorrect:

A: Cisco Prime Service Catalog is a management tool, not part of NFVi infrastructure.

B: Cisco Open vSwitch is not a Cisco product (Open vSwitch is open-source).

E: Cisco Open Container Platform is not part of the NFVi reference solution in conjunction with Red Hat.

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PortFast is a feature that allows access ports to enter the STP forwarding state immediately, without waiting for the usual listening and learning states. This accelerates the connection of end devices like PCs or servers.

A key design benefit is that PortFastdoes not trigger topology changeswhen devices are plugged in or disconnected. This prevents unnecessary STP recalculations and protects core stability.

Correct Statement (A):STP does not consider link transitions on PortFast-enabled ports as topology changes, reducing control-plane overhead.

Other options misrepresent the function of PortFast:

B:PortFast does not disable STP; it bypasses specific STP states.

C/D/E/F:These describe other features like Loop Guard or UDLD, not PortFast.

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NETCONF (Network Configuration Protocol) is a standardized protocol used for automating configuration and management of network devices. According to IETF standards (RFC 6241), the required encoding for NETCONF is:

XML (Extensible Markup Language)

Cisco IOS XE supports NETCONF over SSH and uses XML to structure both configuration data and RPC messages. XML allows strict schema validation (via YANG models), extensibility, and rich hierarchical structure required for modern network automation.

Other formats:

HTML is not a data encoding method.

YAML is typically used with configuration management tools, not NETCONF.

JSON is supported in RESTCONF, not in traditional NETCONF.

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B (R1 adjusts to R2’s Required Min RX):In BFD, each side advertises itsDesired Min TX IntervalandRequired Min RX Interval. Each device adjusts its transmission interval to match the remote side’s ability to receive packets (Required Min RX). So R1 reduces its transmission rate to 100 ms to match R2's platform limitations.

Other options explained:

A: R2 does not adjust to R1’s Desired Min TX; it’s the sender who adapts.

C: BFD quickly converges after initial negotiation.

D: P-bit and F-bit are not involved in this specific interval negotiation.

Comprehensive and Detailed Explanation:

C: Using dynamic routing protocols (e.g., OSPF, EIGRP, or BGP) provides real-time path selection, automatic failover, and improved resiliency. It eliminates manual reconfiguration delays associated with static routing, directly addressing user experience issues during failure.

Other options:

A: QoS improves traffic prioritization, not failover/resiliency.

B: Bandwidth upgrades do not address the failure-handling problem.

D: Adding a third link increases cost without solving the root issue—ineffective routing response.

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In OSPF, a ring topology typically converges more slowly because:

Link failures can create longer SPF recalculations as alternate paths are fewer.

Only one alternate path usually exists for each link failure, extending the time needed for failure detection and SPF recalculation.

CCDE v3.1 stresses that designs like full mesh or triangulated topologies provide faster convergence due to multiple available alternate paths, which reduce SPF computation complexity.

Why other options are incorrect:

A, D, E: These topologies provide multiple paths.

B: Full mesh offers immediate redundancy for any failure.

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In IoT environments, especially in manufacturing plants, security is the primary concern during migration:

IoT devices often have limited security capabilities and may introduce vulnerabilities if not properly segmented, authenticated, and monitored.

Manufacturing plants operate critical systems where availability, safety, and integrity are paramount.

CCDE v3.1 emphasizes securing data, devices, and control systems as a top priority during IoT migrations.

Other options explained:

A: Sensors are part of the IoT solution but not the primary migration concern.

C: Applications are important but typically come after securing connectivity and endpoints.

D/E: Infrastructure elements are secondary to security in the migration assessment.

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A (Device resiliency):Hardware redundancy (dual power supplies, supervisor modules, etc.) ensures device uptime.

D (Network resiliency):Redundant links, fast failover mechanisms, and loop-free designs ensure the overall network remains operational during failures.

Other options explained:

B: Device type is secondary if resiliency features are built-in.

C: Network type is not directly related to resiliency.

E: Network size influences scale, not availability.

Reducing BGP keepalive and hold timers can help improve convergence but must be done carefully in provider-managed networks:

A: The service provider must agree to support modified timers on both PE and CE; otherwise, mismatched timer settings can break neighbor relationships.

C: The service provider may need to schedule configuration changes on PE routers to synchronize the timer adjustments and avoid service interruptions.

Why other options are incorrect:

B: Peer groups simplify policy application but do not impact BGP timers directly.

D: The number of routes affects convergence processing but not directly tied to timer adjustment.

E: The number of VRFs is a scalability consideration but unrelated to BGP timer negotiation.

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In a DMVPN (Dynamic Multipoint VPN) design:

One site (here, Chicago) functions as the Next Hop Server (NHS), which facilitates dynamic spoke-to-spoke tunnel establishment.

DMVPN is based on multipoint GRE tunnels combined with NHRP (Next Hop Resolution Protocol).

The ability to detect remote tunnel endpoint failures is essential for reliable routing convergence and tunnel restoration.

While GRE (Option C) is the encapsulation mechanism used in DMVPN, it does not inherently provide failure detection. Likewise, VPLS and L2TPv3 are Layer 2 VPN technologies and not applicable in DMVPN design.

To meet the requirement of peer failure detection, the correct mechanism is:

B. IP SLA (Service-Level Agreement): This is a feature that actively monitors the health and reachability of tunnel endpoints through periodic probes (e.g., ICMP echo). When the peer becomes unreachable, routing protocol adjacencies can be withdrawn, and alternate paths selected.

Using IP SLA in a DMVPN design helps detect endpoint failure scenarios such as:

A spoke going down unexpectedly

Loss of return traffic

Partial link failures

This design pattern is aligned with CCDE v3.1 "Protocol Design Implications", emphasizing resiliency, fault detection, and efficient routing convergence in overlay VPN designs like DMVPN.

C (Transparent firewall): Operates at Layer 2, allowing filtering and inspection of traffic within the same subnet without requiring IP routing changes. It performs deep packet inspection while maintaining Layer 2 adjacency, making it ideal for intra-subnet traffic control in data centers.

This allows security segmentation inside broadcast domains, enforcing security policies even for east-west traffic.

Other options explained:

A: Routed firewalls require subnet boundaries and are not ideal for intra-subnet control.

B: VLAN ACLs provide basic filtering but lack deep packet inspection capabilities.

D: Zone-based firewalls are primarily designed for inter-subnet (Layer 3) traffic segmentation.

BFD (Bidirectional Forwarding Detection) operates by exchanging control packets between peers, typically using UDP encapsulation. In single-hop deployments, BFD sessions are often established using:

Source IP = destination IP = local interface IP (identical source and destination addresses), especially in certain implementations like Cisco single-hop BFD.

This allows rapid fault detection without routing dependency.

The IPS must permit these packets to avoid disrupting BFD functionality.

Why other options are incorrect:

A: Fragmentation is irrelevant to BFD.

B, C, D, F: BFD does not use broadcast, multicast, or 0.0.0.0 addresses.

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B (Automation spans multiple vendors and services):Automation tools can handle provisioning, configuration, monitoring, and integration across heterogeneous vendor networks.

D (Provisioning services = automation):Routine tasks like service provisioning, device onboarding, or configuration are handled by automation systems to reduce operational workload.

Other options explained:

A: Automation can absolutely include policy enforcement if integrated properly.

C: Orchestration governs higher-level workflows across multiple domains and uses APIs but is not limited to basic automation tasks.

E: Orchestration coordinates complex workflows, not just single low-level tasks.

C (NFV - Network Functions Virtualization):ETSI NFV framework allows virtualizing network functions (firewalls, load balancers, etc.) on standard hardware, promoting flexibility, cost reduction, and hardware independence.

Other options explained:

A: NPIV relates to Fibre Channel storage, not network virtualization.

B: NFVIS is Cisco's NFV infrastructure software, not the ETSI standard itself.

D: VNF refers to individual virtualized functions, not the framework.

Let’s calculate Total Cost of Ownership (TCO) for 24 months based on the table and given scaling requirements:

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Metro Ethernet:

CAPEX = $45,000

Installation Fee = $5,000

OPEX = $125,000/year → $250,000 for 2 years

Total = 45,000 + 5,000 + 250,000 = $300,000

DWDM:

CAPEX = $250,000

Installation Fee = $30,000

OPEX = $100,000/year → $200,000 for 2 years

Total = 250,000 + 30,000 + 200,000 = $480,000

CWDM:

CAPEX = $150,000

Installation Fee = $25,000

OPEX = $100,000/year → $200,000 for 2 years

Total = 150,000 + 25,000 + 200,000 = $375,000

MPLS:

CAPEX = $50,000

Installation Fee = $75,000

OPEX = $150,000/year → $300,000 for 2 years

Total = 50,000 + 75,000 + 300,000 = $425,000

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Metro Ethernet clearly results in the lowest total cost while meeting dual 10G and scalable growth to 20 connections due to its simple provisioning and operational flexibility.

This approach fully aligns with CCDE v3.1 business-driven cost modeling principles: balancing cost, scalability, and operational simplicity.

Why other options are incorrect:

B, C, D: All are more expensive after full 2-year calculation for the required scale.

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In infrastructure design, primary constraints are:

D (Component availability): If hardware or software components are not readily available, designs may need to adapt.

E (Total cost): Budget limitations always influence design decisions regarding redundancy, scalability, and technology selection.

Why other options are not primary constraints:

A: Monitoring is a design consideration, but not a core constraint.

B: Time frame impacts project delivery, not necessarily the design robustness.

C: Staff experience affects operations but is not a primary technical design constraint.

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