N10-009 Practice Test 20 — 15 Questions

Question 1

A network administrator is creating a performance baseline for a new VoIP application. Which metric is most critical to monitor in order to ensure good voice quality for end users?

Accepted Answer

Latency. Latency is the most critical metric for VoIP voice quality because it directly impacts the conversational flow. High latency (above 150 ms one-way, per ITU-T G.114) causes noticeable delays that disrupt natural conversation, leading to user dissatisfaction. While jitter and bandwidth are important, latency is the primary factor that degrades the interactive experience.

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Bandwidth utilization

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Jitter

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Packet loss

Question 2

A company is deploying VoIP phones and wants to ensure voice packets receive priority over data packets on the network. Which technology should be implemented on the switches and routers?

Accepted Answer

Quality of Service (QoS). Quality of Service (QoS) is the correct technology because it allows network devices to classify, mark, and prioritize voice traffic (e.g., using DSCP EF or CoS 5) over data traffic, ensuring low latency, jitter, and packet loss for VoIP. Switches and routers use QoS queuing mechanisms like LLQ or CBWFQ to guarantee bandwidth for voice packets, which is essential for real-time communications.

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VLAN

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Spanning Tree Protocol (STP)

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Power over Ethernet (PoE)

Question 3

A network administrator is creating a standard operating procedure for firmware upgrades. Which step should be performed FIRST according to best practices?

Accepted Answer

Test the firmware in a lab environment. According to best practices for firmware upgrades, the first step should always be to test the new firmware in a non-production lab environment that mirrors the production setup. This validates compatibility, identifies potential bugs, and ensures the upgrade process works without risking network downtime or data loss. Only after successful lab testing should you proceed to backup the current configuration and schedule the upgrade during a maintenance window.

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Schedule the upgrade during a maintenance window

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Back up the current configuration

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Notify users of the planned outage

Question 4

A network technician is explaining the difference between a hub and a switch to a junior technician. Which statement correctly describes a key difference between these devices?

Accepted Answer

A hub sends frames out all ports except the incoming port; a switch sends frames only to the port with the matching MAC address.. B is correct because a hub operates at Layer 1 (physical layer) and blindly repeats electrical signals out all ports except the incoming port, creating a single collision domain. In contrast, a switch operates at Layer 2 (data link layer) and uses the MAC address table to forward frames only to the specific port associated with the destination MAC address, reducing unnecessary traffic and creating separate collision domains per port.

Answer

A hub operates at Layer 2, while a switch operates at Layer 1.

Answer

A hub uses MAC addresses to make forwarding decisions, while a switch uses IP addresses.

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A hub creates a separate collision domain for each port, while a switch creates a single collision domain.

Question 5

A company is deploying a new wireless network for employee devices and wants to use the most secure encryption method currently available for WPA2/3. Which encryption standard should be used?

Accepted Answer

AES. AES (Advanced Encryption Standard) is the most secure encryption method available for WPA2 and WPA3. WPA2 mandates AES-CCMP, and WPA3 uses AES-GCMP, both of which are based on the AES block cipher, providing strong confidentiality and integrity. This makes AES the correct choice for the highest security in modern Wi-Fi deployments.

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WEP

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TKIP

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DES

Question 6

A network engineer needs to connect two network segments that use different physical media: one segment uses copper Ethernet and the other uses fiber optic. The device must forward frames based on MAC addresses and must not perform any routing. Which device should the engineer choose?

Accepted Answer

Bridge. A bridge operates at Layer 2, forwarding frames based on MAC addresses while connecting different physical media (e.g., copper to fiber). It does not perform routing, making it the correct choice for this scenario. Unlike a media converter, a bridge also provides segmentation and collision domain isolation.

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Layer 3 switch

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Media converter

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Router

Question 7

A company is implementing a wireless network and needs to support high-density client environments with minimal interference. Which IEEE 802.11 standard operates in the 5 GHz band and provides the highest throughput among the options?

Accepted Answer

802.11ac. 802.11ac (Wi-Fi 5) operates exclusively in the 5 GHz band and supports up to 8 spatial streams, 256-QAM modulation, and channel bonding up to 160 MHz, yielding theoretical throughput exceeding 6.9 Gbps. This makes it the highest-throughput option among the listed standards for high-density environments with minimal interference, as the 5 GHz band offers more non-overlapping channels and less co-channel contention than 2.4 GHz.

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802.11n

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802.11g

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802.11b

Question 8

An NOC technician receives an alert that latency on a critical WAN link has increased significantly. The technician needs to analyze the latency trend over the past week to identify patterns. Which approach is the most efficient for gathering this historical data?

Accepted Answer

Use SNMP polling with a suitable MIB to collect latency metrics at regular intervals. SNMP polling with a suitable MIB (e.g., IF-MIB for interface statistics or IP-MIB for performance metrics) allows the NOC to collect latency data at regular, configurable intervals over time. This historical data can be stored in a management system and analyzed for trends, making it the most efficient method for identifying patterns in WAN latency over a week. SNMP traps, by contrast, are event-driven and do not provide the continuous, periodic data needed for trend analysis.

Answer

Use SNMP traps to alert on each latency spike

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Run a continuous ping test and manually log timestamps

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Use traceroute to identify each hop and measure latency per hop

Question 9

A technician is troubleshooting intermittent wireless connectivity in a conference room. A site survey shows strong signal strength but many nearby access points are using channels that overlap with the channel used by the conference room AP. Which of the following is the most likely cause of the issue?

Accepted Answer

Adjacent channel interference from access points on overlapping channels.. The site survey shows strong signal strength but many nearby access points are using channels that overlap with the channel used by the conference room AP. This directly indicates adjacent-channel interference (ACI), where overlapping channels (e.g., channels 1, 2, 3, 4, and 5 all overlap with channel 1 in the 2.4 GHz band) cause contention and retransmissions, degrading performance even with strong signal. ACI is the most likely cause because the overlapping channels create co-existence issues without being on the exact same channel.

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Multipath interference from reflective surfaces.

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Co-channel interference from access points on the same channel.

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Signal attenuation due to distance from the AP.

Question 10

An NOC technician observes that the average latency on a critical WAN link has risen sharply. To determine which applications are consuming the most bandwidth and contributing to the latency, which tool should the technician use?

Accepted Answer

A) NetFlow. NetFlow is the correct tool because it provides per-flow traffic analysis, allowing the technician to identify which applications (by protocol and port) are consuming the most bandwidth on the WAN link. Unlike simple bandwidth monitors, NetFlow exports detailed records of source/destination IPs, ports, and byte counts, enabling precise identification of bandwidth-hungry applications contributing to increased latency.

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B) SNMP

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C) Syslog

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D) Ping

Question 11

A company wants to prevent unauthorized users from plugging into network jacks and gaining access to the wired network. Which of the following security mechanisms should be implemented at the switch level?

Accepted Answer

802.1X. 802.1X is a port-based Network Access Control (NAC) standard (IEEE 802.1X) that authenticates devices before granting full network access. When a device plugs into a switch port, the switch (as the authenticator) blocks all traffic except EAPoL (Extensible Authentication Protocol over LAN) frames until the device successfully authenticates via a RADIUS server. This prevents unauthorized users from gaining network access simply by connecting to a live jack.

Answer

MAC address filtering

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Port security

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Dynamic ARP Inspection

Question 12

A network administrator needs to monitor network traffic to identify which hosts are consuming the most bandwidth. Which of the following tools is BEST suited for this task?

Accepted Answer

NetFlow. NetFlow is the best tool for monitoring network traffic to identify bandwidth consumption by hosts because it collects and analyzes IP traffic flow data, providing detailed visibility into source/destination IPs, protocols, and byte counts. Unlike simple interface counters, NetFlow allows an administrator to pinpoint which specific hosts are generating the most traffic, making it ideal for bandwidth usage analysis.

Answer

Syslog server

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SNMP trap

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Traceroute

Question 13

A network administrator needs to connect two buildings 2 km apart using single-mode fiber. Which transceiver type should be used?

Accepted Answer

1000BASE-LX. 1000BASE-LX (Long Wavelength) operates at 1310 nm over single-mode fiber and supports distances up to 5 km (and often up to 10 km with proper link budgets), making it the correct choice for a 2 km link. Single-mode fiber is required for distances beyond 550 m, and 1000BASE-LX is the Gigabit Ethernet standard designed for such single-mode runs.

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1000BASE-T

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1000BASE-SX

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10GBASE-SR

Question 14

A network administrator is setting up SNMPv3 on a router for secure monitoring. Which of the following is required for SNMPv3 authentication?

Accepted Answer

Username and password. SNMPv3 introduces a security model that requires a username and password (authentication passphrase) for authentication, moving away from the community-string-based model of SNMPv1/v2c. The password is used with an authentication protocol like MD5 or SHA to verify the identity of the manager before allowing access. Without a valid username and password combination, SNMPv3 will reject the request.

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Community string

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Encryption key

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Public key

Question 15

A security analyst is reviewing DHCP server logs and notices that a single MAC address is sending an extremely high number of DHCP discover packets. The DHCP server is responding, but the client never sends a DHCP request. Which type of attack is most likely occurring?

Accepted Answer

A) DHCP starvation. A DHCP starvation attack works by flooding the DHCP server with DHCPDISCOVER packets from spoofed MAC addresses, exhausting the server's IP address pool. In this scenario, a single MAC address sending excessive DHCPDISCOVER packets without completing the DORA handshake (no DHCPREQUEST) is a classic indicator of a starvation attack, as the attacker aims to consume all available leases and cause a denial of service for legitimate clients.

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B) ARP poisoning

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C) MAC flooding

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D) DNS spoofing