400-007 Exam Dumps - Cisco CCDE v3.0 Questions and Answers

C (Transparent firewalling):Transparent (Layer 2) firewalls operate at the data link layer and allow segmentation and inspection of intra-VLAN traffic without requiring changes to the existing IP addressing. This is ideal for legacy environments where IP addresses are hard-coded, while still providing fine-grained security policies between applications in the same subnet.

Other options explained:

A: Perimeter firewalls cannot segment east-west traffic within a VLAN.

B: VACLs provide basic filtering but are not as scalable or flexible as transparent firewalls for stateful inspection.

D: Routed firewalls require Layer 3 boundaries, which would conflict with hard-coded IP design.

A (Route Reflector design): Using R5 as a route reflector reduces the IBGP full-mesh requirement while maintaining route visibility between R1, R2 (edge) and R3, R4 (ABRs).

Internet routes can be redistributed into OSPF at the edge routers (R1, R2), allowing internal reachability while avoiding redistribution complexity on every router.

Why other options are incorrect:

B: Sub-AS designs (confederations) add unnecessary complexity for this scenario.

C: Full mesh IBGP is not scalable with increasing n odes.

D: Not using a route reflector would force full mesh IBGP.

EIGRP’s convergence time is heavily impacted by the size of the query domain — the group of routers involved when a route goes into active state. The larger the query domain, the longer the convergence. Summarization naturally bounds query propagation because routers receiving a summary have no knowledge of individual prefixes beyond that summary, preventing them from being queried about specifics they don’t track.

This design technique is emphasized in CCDE v3.1 because:

Summarization reduces the query scope.

Faster convergence happens as fewer routers process queries.

Hierarchical design is enabled for stability and scalability.

Why other options are incorrect:

A: Distribute lists filter prefixes but don ' t reduce query propagation.

B and C: Triangulated or squared physical topology doesn’t control protocol-level query scope.

E: Default routes may help limited routing domains but don’t optimize EIGRP convergence specifically.

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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.

B (Route dampening): Route dampening suppresses the advertisement of flapping routes in BGP to protect the stability of the routing domain. Once the penalty threshold is reached, the unstable route is suppressed temporarily, preventing frequent updates from impacting the rest of the BGP network.

Other options explained:

A: Aggregation may help, but if the summary includes unstable subnets, flapping may still affect the summary.

C/D: Filtering removes the route entirely, which may be undesirable if occasional reachability is still needed.

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A (Working design over documentation):Agile prioritizes functional working solutions over exhaustive documentation, allowing continuous delivery and adaptability during the project lifecycle.

Other options explained:

B: Agile favors customer collaboration over contract negotiation.

C: Agile favors responding to change over rigid planning.

D: Agile favors individuals and interactions over processes and tools.

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.