Free Practice Questions for Cisco 400-007 Exam

Route Distinguishers (RDs) are fundamental to MPLS Layer 3 VPN architecture (RFC 4364). They allow the service provider to distinguish identical IP prefixes from different VPN customers by adding a unique identifier to each VPN route, preventing conflicts from overlapping IP spaces.

Unique RDs ensure that the VPNv4 address family maintains separation of identical customer prefixes.

Why other options are incorrect:

B: Route Targets control route import/export policy but do not differentiate overlapping prefixes.

C: NAT is not required inside MPLS VPN for overlapping IPs.

D: VRF IDs are local identifiers on routers; not relevant for prefix uniqueness in control plane.

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MLD (Multicast Listener Discovery) snooping for IPv6 operates similarly to IGMP snooping in IPv4. It tracks listener reports to restrict multicast flooding within a Layer 2 domain.

C: Querier elections are triggered when a querier becomes unreachable or its IP address changes.

D: The querier with the lowest IPv6 address is elected as the active querier, which manages report/query communication.

Other options:

A: QoS is not automatically enabled with MLD snooping.

B: MLD querier functionality operates per VLAN—not per group—so only one querier is elected per VLAN.

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Comprehensive and Detailed Explanation:

To reduce oscillation and improve resiliency:

D: Increasing unequal-cost multipath (UCMP) paths allows the routing protocol to load-share over more than one path, preventing traffic congestion from oscillating between nodes.

E: Dual links to each site improve bandwidth and failover options, reducing reliance on overloaded peers.

Other options:

A: Increasing redundant paths may worsen convergence complexity and doesn ' t solve oscillation.

B: Removing inter-spoke links reduces redundancy.

C: Increasing convergence timers delays recovery and stability.

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In this architecture:

A secure web proxy is introduced to inspect and filter all web (HTTP/HTTPS) traffic.

Remaining traffic (non-web) must pass through an NGFW with IPS capabilities.

Both the web proxy and NGFW reside between the collapsed distribution/core and internet edge.

To enforce that all web traffic is directed to the proxy appliance for inspection and non-web traffic follows its usual path to the NGFW:

A. Policy-Based Routing (PBR) on the Collapsed Core

This allows traffic classification based on destination port (e.g., TCP 80/443) and selectively reroutes web traffic to the proxy. Non-web traffic continues toward the NGFW. PBR is essential here because traditional routing (based only on destination IP) would not differentiate between traffic types.

D. Static Routing on the Appliance

The proxy appliance must return the traffic back toward the NGFW for final processing and internet egress. This is typically achieved using static routes on the proxy device, ensuring the return path sends packets back to the correct firewall interface for consistent inspection.

❌ B. Policy-based routing on the internet edge: Not applicable here, as rerouting must occur closer to the source (collapsed core), before traffic reaches the internet edge.

❌ C. Policy-based routing on firewalls: This adds unnecessary complexity. Firewalls should focus on enforcing security policies, not traffic redirection logic in this scenario.

This approach adheres to CCDE v3.1 best practices by separating policy enforcement functions and enabling scalable, deterministic traffic flow through layered security appliances.

The distribution layer serves as the boundary between the access and core layers in the three-tier hierarchical design. It plays a crucial role in providing policy enforcement, control, and boundary functions, including:

QoS classification and marking (C): The distribution layer serves as the boundary for Quality of Service policies. It marks and classifies traffic as it moves from access to core layers, ensuring proper QoS treatment in the core.

Redundancy and load balancing (E): The distribution layer provides link redundancy (e.g., dual-homing access layer switches) and performs load balancing to optimize path selection toward the core.

Other options explained:

A (Fast transport): Typically associated with the core layer, which focuses on high-speed forwarding.

B (Reliability): While reliability is a network-wide goal, it’s not a primary function of the distribution layer specifically.

D (Fault isolation): While partial fault containment occurs, primary fault isolation happens at the access layer.

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D (SAML2.0):SAML2.0 is widely used for federated identity management in enterprise environments, supporting Single Sign-On (SSO) across multiple applications and domains.

Other options explained:

A: OAuth2 is primarily for authorization, not identity federation.

B: OpenID Connect extends OAuth2 for authentication but is more common for consumer web apps than enterprise SSO.

C: OpenID is older and largely replaced by OpenID Connect.

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.

The design requires scalability, centralized credential management, device independence, and role-based access:

B (Central authentication directory): A centralized directory (such as Active Directory, RADIUS, or LDAP) allows the VPN solution to leverage existing user credentials, support role-based access control, and scale easily.

F (SSL VPN): Provides remote access VPN services that support a variety of client devices, including unmanaged or personal devices, without requiring device certificates. SSL VPN is well-suited for scenarios where users may not always use the same device.

Other options explained:

A: Local usernames/passwords do not scale to thousands of users and lack centralized policy control.

C/E: Certificates would require device management and may not be feasible if users switch devices.

D: IPsec VPN can work, but typically requires more complex client configuration and may not support flexible device usage as well as SSL VPN.

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