N10-009 Network Implementation Practice Test 4 — 15 Questions

Question 1

A network architect is designing a Software-Defined Networking (SDN) based network. Which of the following components is responsible for making centralized forwarding decisions and communicating those decisions to the physical switches using southbound APIs?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Control layer. In SDN architecture, the control layer (also known as the SDN controller) is the centralized entity responsible for making all forwarding decisions. It communicates these decisions to the physical switches via southbound APIs, such as OpenFlow, which program the flow tables in the data plane. This separation of the control plane from the data plane is the fundamental principle of SDN.

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Application layer

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Data plane

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East-west interfaces

Question 2

A network engineer is implementing OSPF on a router. All directly connected neighbors are listed with state FULL, but routes from another area are not appearing in the routing table. Which of the following is the most likely cause?

Accepted Answer

The router has an ACL blocking inbound OSPF updates. An ACL applied to the OSPF process or interface can filter inbound Type 3 LSAs (summary LSAs) from other areas. Even though neighbor adjacencies reach FULL state, the router will not install those inter-area routes into the routing table if the ACL blocks the LSA updates. This explains why directly connected neighbors are fine but routes from another area are missing.

Answer

The router is not configured with a router ID

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The router is configured as an ABR but does not have a virtual-link configured

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The link-state database is corrupted

Question 3

A network administrator is configuring Quality of Service (QoS) on a router to prioritize voice traffic. Which of the following fields should be used to mark packets for classification and prioritization?

Accepted Answer

DSCP. DSCP (Differentiated Services Code Point) is the correct field because it is a 6-bit value in the IP header used to mark packets for QoS classification and prioritization, as defined in RFC 2474. Voice traffic typically uses DSCP EF (Expedited Forwarding, value 46) to ensure low latency and jitter, making it the standard choice for QoS marking on routers.

Answer

Source IP address

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Source port number

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MAC address

Question 4

A network administrator is designing a Layer 2 network with redundant links between switches. Which protocol should be implemented to prevent loops in the network?

Accepted Answer

STP (Spanning Tree Protocol). STP (Spanning Tree Protocol) is the correct choice because it is specifically designed to prevent Layer 2 loops in networks with redundant links. It achieves this by placing redundant switch ports into a blocking state, creating a loop-free logical topology while maintaining physical redundancy for failover.

Answer

OSPF (Open Shortest Path First)

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VRRP (Virtual Router Redundancy Protocol)

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LACP (Link Aggregation Control Protocol)

Question 5

A network architect is implementing a Software-Defined Networking (SDN) solution. The SDN controller needs to communicate with the physical switches to install flow rules. Which type of API is used for this communication?

Accepted Answer

Southbound API. The Southbound API is the correct interface because it enables the SDN controller to communicate with the underlying physical or virtual network devices (switches, routers) to install flow rules, modify forwarding tables, and gather telemetry. This API typically uses protocols such as OpenFlow, NETCONF, or OVSDB to translate controller decisions into device-level actions, making it the essential southbound channel in an SDN architecture.

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Northbound API

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Eastbound API

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Westbound API

Question 6

A network administrator is creating a new VLAN that will contain 20 devices. The administrator wants to use the most efficient subnet that provides enough usable IP addresses while minimizing waste. Which of the following subnet masks should be used?

Accepted Answer

255.255.255.224 (/27). A /27 subnet mask (255.255.255.224) provides 32 total addresses, of which 30 are usable (2^5 - 2 = 30). This is the most efficient choice for 20 devices because it offers exactly enough usable IPs with minimal waste (only 10 unused addresses), whereas a /28 would provide only 14 usable addresses (insufficient) and a /29 would provide only 6 usable addresses (also insufficient).

Answer

255.255.255.240 (/28)

Answer

255.255.255.248 (/29)

Answer

255.255.255.192 (/26)

Question 7

A network administrator is installing cable in a plenum space (an area used for air circulation, such as above a drop ceiling). Which cable type is required by most building codes for such an installation?

Accepted Answer

Plenum-rated cable. Plenum-rated cable is required by most building codes (e.g., NFPA 70, National Electrical Code) for installation in plenum spaces because it is constructed with fire-retardant materials, such as FEP or PFA, that produce minimal smoke and are self-extinguishing. This prevents toxic fumes and flames from spreading through air-handling areas, ensuring safety in case of a fire. Standard PVC-jacketed cable would release hazardous smoke and support flame propagation, making it illegal in plenum spaces.

Answer

PVC-jacketed cable

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Riser-rated cable

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Low Smoke Zero Halogen (LSZH) cable

Question 8

A network engineer needs to connect two switches that are located 450 meters apart. Which combination of fiber optic transceiver and cable type would support the highest data rate over this distance?

Accepted Answer

10GBASE-LR with single-mode fiber. 10GBASE-LR (Long Reach) supports 10 Gbps over single-mode fiber (SMF) up to 10 km, easily covering the 450-meter distance. Single-mode fiber has a smaller core (9 µm) that minimizes modal dispersion, enabling higher data rates over longer distances compared to multimode fiber. This combination provides the highest data rate (10 Gbps) among the options for the given distance.

Answer

10GBASE-SR with multimode fiber

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1000BASE-LX with single-mode fiber

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1000BASE-SX with multimode fiber

Question 9

A network engineer needs to deploy a new wireless network in a large office with many cubicles. The goal is to provide high throughput and support multiple simultaneous users. Which IEEE standard should be implemented?

Accepted Answer

802.11ac. 802.11ac (Wi-Fi 5) operates exclusively in the 5 GHz band, uses wider 80 MHz or 160 MHz channels, and supports MU-MIMO (Multi-User Multiple Input Multiple Output) to deliver high throughput and efficient handling of multiple simultaneous users in a dense office environment. This makes it the best choice among the options for a modern, high-capacity wireless deployment.

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802.11n

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802.11b

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802.11g

Question 10

A company is connecting two buildings that are 300 meters apart. The link must support 10 Gbps. Which combination of cable and transceiver should be used?

Accepted Answer

Single-mode fiber with 10GBASE-LR. Single-mode fiber (SMF) with 10GBASE-LR supports 10 Gbps over distances up to 10 km, easily covering the 300-meter requirement. 10GBASE-LR uses 1310 nm laser optics over single-mode fiber, providing low signal loss and high bandwidth for long-reach links.

Answer

Cat6a UTP with 10GBASE-T

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Cat5e UTP with 1000BASE-T

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Multimode fiber with 10GBASE-SR

Question 11

A network administrator is configuring a new switch to carry traffic for multiple VLANs on a single link to a router. Which IEEE standard is used for VLAN tagging on Ethernet trunks?

Accepted Answer

802.1Q. 802.1Q is the IEEE standard that defines VLAN tagging on Ethernet trunks, inserting a 4-byte tag into the Ethernet frame to identify VLAN membership. This allows multiple VLANs to traverse a single link between a switch and a router, enabling inter-VLAN routing without separate physical interfaces.

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802.3af

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802.1D

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802.11ac

Question 12

A small office has multiple devices that need internet access but the ISP provides only a single public IPv4 address. Which network address translation (NAT) technique is most appropriate to allow all internal hosts to share that one public address?

Accepted Answer

PAT (Port Address Translation). PAT (Port Address Translation), also known as NAT overload, is the correct choice because it allows multiple internal hosts to share a single public IPv4 address by mapping each unique internal IP:port combination to a different source port on the public address. This is the only NAT technique that provides many-to-one address translation, which is exactly what a small office with more devices than public IPs requires.

Answer

Static NAT

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Dynamic NAT

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IP masquerading

Question 13

A network engineer is designing a wireless network for a large warehouse with many metal racks and heavy machinery that cause significant RF interference. The network must support a high density of IoT sensors and provide reliable connectivity. Which IEEE wireless standard should the engineer implement to best meet these requirements?

Accepted Answer

802.11ax (Wi-Fi 6). 802.11ax (Wi-Fi 6) is the correct choice because it introduces Orthogonal Frequency Division Multiple Access (OFDMA), which subdivides channels into smaller resource units (RUs) to serve multiple IoT sensors simultaneously, improving efficiency in dense, interference-heavy environments. Additionally, Wi-Fi 6 includes BSS Coloring, which reduces co-channel interference by allowing devices to ignore transmissions from overlapping basic service sets, and Target Wake Time (TWT), which schedules IoT sensor transmissions to conserve battery and reduce contention.

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802.11ac (Wi-Fi 5)

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802.11n (Wi-Fi 4)

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802.11g (Wi-Fi 3)

Question 14

A network engineer is designing a new switched network and needs to ensure that broadcast traffic from one department does not reach another department's workstations. The engineer plans to use VLANs. Which of the following must be configured on the switches to isolate broadcast domains as intended?

Accepted Answer

Assign each department's workstations to a unique VLAN and configure their switch ports as access ports in that VLAN.. VLANs segment a switched network into separate broadcast domains at Layer 2. By assigning each department's workstations to a unique VLAN and configuring their switch ports as access ports in that VLAN, broadcast traffic from one VLAN is confined to that VLAN and cannot reach workstations in another VLAN. This achieves the isolation required without additional filtering devices.

Answer

Configure all switch ports as trunk ports and use VLAN 1 for all departments.

Answer

Place all workstations in the same VLAN and use a firewall to filter broadcast traffic between departments.

Answer

Configure each switch port as a trunk and use a different native VLAN for each department.

Question 15

A network engineer is planning to connect two switches that are 150 meters apart. The link must support at least 1 Gbps and the budget is limited. Which cable type should be used?

Accepted Answer

Multimode fiber optic. Multimode fiber optic cable supports 1 Gbps over distances up to 550 meters (OM2) or more, easily covering the 150-meter requirement at a lower cost than single-mode fiber. It is the best choice for this distance and budget because twisted-pair copper (Cat5e/Cat6a) is limited to 100 meters for 1 Gbps, and single-mode fiber is more expensive due to laser-based transceivers.

Answer

Cat6a twisted-pair copper

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Single-mode fiber optic

Answer

Cat5e twisted-pair copper