Pass the Cisco CCDE v3.0 400-007 Questions and answers with CertsForce

D (Route maps with tags): When redistributing between OSPF domains at multiple locations (mutual redistribution), route tagging is a key technique to prevent routing loops. Each ASBR applies route tags on incoming routes, and redistribution policies check these tags to prevent re-advertising routes that originated from the other domain.

Other options explained:

A: Virtual links are for connecting discontiguous OSPF areas, not preventing redistribution loops.

B: Router ID uniqueness is required but does not prevent loops.

C: External type 2 redistribution doesn't inherently prevent loops.

E (Infrastructure ACLs): iACLs control what traffic can reach network infrastructure devices, directly securing the data plane.

G (Routing Protocol Authentication): Prevents malicious or spoofed routing updates which directly protect data plane routing decisions.

Why other options are incorrect:

A: Warning banners are management plane hardening.

B: Redundant AAA is management/control plane hardening.

C: CPPr protects the control plane.

D: SNMPv3 secures management plane.

F: Disabling unused services typically applies to management plane or control plane, not data plane.

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Agile project management supports:

Frequent updates and iterative feedback loops

Flexibility to accommodate evolving requirements

Continuous customer collaboration and transparency

This methodology is ideal for projects where scope may shift and customer involvement is essential. In contrast:

Waterfall is linear and rigid

Phased delivery segments milestones but limits change midstream

“Three principles” is not a recognized methodology in this context

Agile aligns with modern IT deployment models and is supported in CCDE methodology as a business-aligned and adaptive design execution strategy.

When OSPF operates over a broadcast network (such as Ethernet), it uses the DR (Designated Router) and BDR (Backup Designated Router) mechanism to reduce adjacency overhead. Instead of forming full mesh adjacencies, OSPF routers establish full neighbor relationships only with the DR and BDR.

For five routers:

Each router establishes a full adjacency with the DR and the BDR.

The DR and BDR also establish adjacency with each other.

Total number of fully established adjacencies = 5 (each router to DR/BDR).

Partial adjacencies (2-way) may exist among DROther routers, but those are not fully established neighbor relationships (i.e., not exchanging LSDBs).

This design behavior is emphasized in CCDE v3.1 to avoid excessive LSDB flooding and optimize control-plane scaling.

Why other options are incorrect:

B, C, D, E: These assume full mesh adjacencies or incorrect OSPF behavior for broadcast networks.

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In the design ofIPv6 multicast services, particularly usingPIM Sparse Mode, thefirst-hop router(which is connected to the multicast source) must register the multicast source with theRendezvous Point (RP). This registration involves encapsulating the multicast packets in unicast messages and sending them to the RP.

This encapsulation is done over adynamically created tunnel interface, typically referred to as aPIM Register Tunnel. This temporary tunnel is established by the source-side router to send encapsulated multicast traffic to the RP for initial source registration.

Therefore, the dynamic tunnel serves the purpose of:

Encapsulating and sending the first multicast packets from the source to the RP

Allowing the RP to learn about new sources and initiate shared tree or shortest-path tree forwarding

This operation aligns with CCDE v3.1 design principles, where understanding the internal operation of multicast protocols—especially source registration and RP role—is critical for scalable and reliable multicast service delivery.

Why other options are incorrect:

A: First-hop router doesn’t register itself, it registers thesourceto the RP.

B: Clients (receivers) do not register to the RP; they send IGMP/MLD joins which flow toward the RP.

D: Not all IPv6 multicast traffic is transported via tunnels; only initial registration traffic is encapsulated in this manner.

This mechanism is essential for source discovery in sparse-mode multicast and is foundational to multicast tree building in IPv6 networks.

While the Agile Manifesto itself is not a network-specific construct, its values are relevant to business-driven network design approaches outlined in CCDE v3.1—especially when designing flexible and adaptive systems. One of the core values of Agile is:

→ “Individuals and interactions over processes and tools”

This emphasizes that communication and collaboration among people are more crucial than relying solely on formal tools or rigid processes. For network architects and designers, this translates into focusing on team collaboration and business alignment during iterative design cycles.

Incorrect Options:

A, B, and D are all reversed versions of Agile’s actual values; they incorrectly prioritize the right-hand side.

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D (Enables innovation):SDN allows new services, business models, and automation capabilities.

E (OpEx/CapEx reduction):Automation reduces operational effort, and commodity hardware reduces CapEx.

Other options explained:

A: Redundancy depends on physical design.

B: SDN centralizes management.

C/F: SDN doesn't directly impact latency or capacity.

Automation: The execution of individual tasks or configurations without manual intervention.

Orchestration: The coordination and sequencing of multiple automation tasks into structured workflows to achieve complex operational goals.

Why other options are incorrect:

B, C, D: They incorrectly define orchestration as either partially manual, parallel execution, or limited to commercial tools, which is not accurate in design principles.

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D: CWDM (Coarse Wavelength Division Multiplexing) shares parts of the same optical transmission window (1260–1625 nm) as DWDM but uses wider spacing between channels (typically 20 nm apart).

E: CWDM typically uses passive devices (multiplexers and demultiplexers) that require no electrical power, making deployment cost-effective.

Incorrect Options:

A: CWDM is better suited for shorter distances (up to ~80 km) and doesn't typically use optical amplifiers (EDFA). DWDM is better for long-haul with amplification.

B: 850 nm is used in multimode fiber systems (not CWDM).

C: CWDM supports up to 18 channels; DWDM supports up to 32 or more.

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