Free Cisco 400-007 Practice Exam with Questions & Answers | Set: 7

Loop Guardis designed to protect againstSTP loop conditionsthat may occur whenBPDUs are unexpectedly missingon a point-to-point link. This is especially relevant in cases where UDLD (Unidirectional Link Detection) might not detect the problem quickly enough. When BPDUs are absent, a switch might erroneously assume that the link is safe to forward, potentially leading to atemporary Layer 2 loop.

UsingLoop Guardensures that a port moves into aloop-inconsistentstate instead of forwarding traffic if BPDUs are missing, effectively stopping a loop before it forms. This makes it acomplementary mechanism to UDLD, which focuses on detecting unidirectional links at the physical layer, not STP control plane failures.

This recommendation aligns with CCDE v3.1 best practices forresilient Layer 2 designs, which emphasize using multiple mechanisms in tandem to proactively prevent failure conditions before traffic is impacted.

Why other options are incorrect:

A. Root Guard: Prevents an unauthorized switch from becoming the root bridge but doesn ' t protect against missing BPDUs.

B. BPDU Guard: Used mainly on access ports to prevent BPDU reception; not intended for core loop prevention.

D. BPDU Filtering: Suppresses BPDU exchange entirely, which increases loop risk and is not suited for loop mitigation.

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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A: Flow-based analysis allows understanding bandwidth usage across apps and sessions, crucial for voice/video capacity management.

C: Call management systems track CAC and call quality failures, key for voice/video troubleshooting.

D: Active synthetic probes proactively inject traffic to monitor loss, latency, and jitter under real-time conditions.

Why other options are incorrect:

B: Network convergence is not directly analyzed through call management tools.

E: Passive synthetic probes is not an accurate term; passive monitoring refers to analysis of real traffic flows, not synthetic tests.

F: PTP time-stamping is more applicable to clock synchronization, not regular voice/video performance monitoring.

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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B (Weighted Random Early Detection - WRED):WRED proactively drops packets before buffers are full to avoid global synchronization in TCP traffic and prevent tail drops, thus improving overall TCP performance under congestion.

Other options explained:

A: WFQ provides fairness but does not proactively avoid congestion.

C: LLQ is for delay-sensitive traffic, not congestion avoidance for TCP.

D: FIFO offers no QoS or congestion control.

D (LISP — Locator/ID Separation Protocol):

Supports massive scale with centralized control plane (mapping servers).

CE routers do not run routing protocols with PE.

Allows load balancing and multi-homing using locator sets.

Supports IPv4 and IPv6.

Lightweight CE requirements fit low-cost platforms.

Why other options are incorrect:

A: FlexVPN is control-plane intensive and less scalable for large managed CE deployments.

B: Point-to-point GRE doesn ' t scale well with 250,000 CEs.

C: DMVPN requires routing protocol overlays which violate the requirement.

Ansible is an open-source automation tool that enables configuration management, application deployment, cloud provisioning, and orchestration.

It uses simple YAML-based playbooks and SSH-based connectivity, making it agentless, highly scalable, and easy to integrate with networking environments.

Commonly adopted in network automation, cloud infrastructure provisioning, and service orchestration as part of modern network design practices covered under CCDE v3.1.

Why other options are incorrect:

B (Contrail): Network virtualization platform, not primarily an automation tool.

C (Java): General-purpose programming language, not specifically designed for infrastructure automation.

D (Jinja2): Templating engine, used inside Ansible but not an automation tool by itself.

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???? Explanation:

B: To prefer ISP 1 for outbound traffic, advertise a longer AS path to ISP 2 (so it ' s used as backup). To prefer ISP 1 for inbound traffic, you want ISP 2 to receive a higher MED, making it less preferred. These changes signal to both ISPs and remote ASes to prioritize the ISP 1 path.

Other options:

A: Local preference is set inbound by your own routers, not outbound to ISPs.

C: Local preference affects only your own AS, and more specific routes are better advertised on primary links, not secondary.

D: Advertising less specific routes does not help establish control over preference cleanly.

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???? QUESTION NO: 387 [Security, Automation, and Policy Integration in Design]

Which three components support enforcing security policy compliance for devices attempting network access? (Choose three)

A. Posture agent

B. Audit and decision point servers

C. Management and reporting tools

D. Endpoint security application

E. Network access devices

F. Web filtering devices

Answer: A, B, E

???? Explanation:

A: Posture agents assess the health of endpoints (e.g., antivirus status, OS patching).

B: Decision servers (e.g., Cisco ISE) enforce access decisions based on posture and policies.

E: Network access devices (e.g., switches, WLCs, routers) apply access controls based on server instructions (802.1X, NAC).

Other options:

C: Management tools are for visibility—not enforcement.

D: While useful, endpoint AV/firewalls act independently—not part of policy enforcement infrastructure.

F: Web filters do not participate in initial access decisions.

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???? QUESTION NO: 388 [Security, Automation, and Policy Integration in Design]

When are Network Behavior Anomaly Detection (NBAD) systems better than signature-based systems? (Choose two)

A. Malware detection

B. Encrypted threat traffic

C. Spyware detection

D. Intrusion threat detection

E. New zero-day attacks

Answer: B, E

???? Explanation:

B: Signature-based systems cannot inspect encrypted payloads effectively, whereas NBAD relies on traffic behavior.

E: NBAD identifies deviations from known good behavior, allowing detection of previously unknown (zero-day) threats.

Incorrect Options:

A, C, D: These are often more accurately detected using signature-based approaches where known

???? QUESTION NO: 389

[Main Topic: Security, Automation, and Policy Integration in Design]

A company is adopting IPv6 in a dual-stack campus network. The first IPv6-only application is now hosted in the data center. To prevent a malicious user from masquerading as the IPv6 default gateway, which two mechanisms should be used? (Choose two)

A. IPv6 RA guard

B. IPv6 snooping

C. IPv6 device tracking

D. IPv6 address glean

E. port ACLs

Answer: A, E

???? Comprehensive and Detailed Explanation (CCDE v3.1 aligned):

A. IPv6 RA Guard:This feature helps mitigate rogue router advertisements (RAs), which attackers can use to spoof the default gateway in an IPv6 environment. RA Guard drops unauthorized or unexpected RAs at the access layer switch ports, preventing malicious devices from advertising themselves as routers.

E. Port ACLs (PACLs):Port-based ACLs can restrict which devices are allowed to send or receive RA packets on switch ports. By tightly controlling which sources can send traffic (including RA messages), port ACLs help prevent spoofing attempts.

Other Options:

❌ B. IPv6 Snooping:Not a standard or widely supported security feature; it is sometimes used synonymously with device tracking but is not a direct mitigation for spoofed RAs.

❌ C. IPv6 Device Tracking:Useful for monitoring IP-to-MAC bindings, but it does not prevent spoofing or gateway impersonation.

❌ D. IPv6 Address Glean:Primarily used for learning IPv6 addresses from traffic for things like DHCPv6 relay; not a security feature.

CCDE Blueprint Alignment:

Topic: Security, automation, and policy integration in design

Subdomain: IPv6 security, access control, rogue device prevention.

Let me know if you ' d like the next question explained!

A (TRILL - Transparent Interconnection of Lots of Links):TRILL enables multipathing at Layer 2, eliminating classic STP blocking, allowing all uplinks to be active simultaneously, and uses IS-IS based control plane for conversational MAC learning.

Other options explained:

B: LISP operates at Layer 3 for endpoint mobility, not Layer 2 multipathing.

C: MSTP still blocks some links under normal operation.

D: Switch stacking merges multiple physical switches into one logical switch but does not provide true multipathing across independent switches.