N10-009 Practice Test 2 — 25 Questions

Question 1

A network administrator wants to ensure all network devices have synchronized time for accurate log correlation and security event analysis. Which protocol should be implemented?

Accepted Answer

NTP. NTP (Network Time Protocol) is the correct choice because it is specifically designed to synchronize clocks across network devices using a hierarchical system of time sources, ensuring millisecond-level accuracy. Accurate time synchronization is critical for correlating logs and security events across multiple devices, as timestamps must match to reconstruct attack timelines or diagnose faults.

Answer

SNMP

Answer

FTP

Answer

HTTP

Question 2

A switch is connected to a network printer. The switch port is manually configured for 100 Mbps and full duplex. The printer is configured for auto-negotiation. The link is up, but there are many FCS errors on the switch port. What is the most likely cause?

Accepted Answer

Duplex mismatch. The most likely cause is a duplex mismatch. The switch port is manually set to full duplex, while the printer is using auto-negotiation. When one side is manually configured and the other is set to auto-negotiation, the auto-negotiating side fails to detect the manual setting and defaults to half duplex. This mismatch causes collisions and frame check sequence (FCS) errors on the full-duplex side, as the half-duplex side does not properly handle simultaneous transmission.

Answer

Bad Ethernet cable

Answer

Speed mismatch

Answer

Printer driver issues

Question 3

Which of the following uniquely identifies a hardware network interface on a device?

Accepted Answer

MAC address. A MAC (Media Access Control) address is a hardware-embedded, globally unique identifier assigned to a network interface controller (NIC) by the manufacturer. It operates at Layer 2 (Data Link Layer) of the OSI model and is used for local network communication, ensuring that no two devices on the same broadcast domain have the same MAC address.

Answer

IP address

Answer

Subnet mask

Answer

Default gateway

Question 4

A network administrator has configured a switch with four VLANs: VLAN 10, 20, 30, and 99 (native). The switch is connected to a router via an 802.1Q trunk link. The router has subinterfaces for VLANs 10, 20, and 30, each with an IP address. VLAN 99 is used for management and does not have a router subinterface. How many Layer 3 broadcast domains exist in this network?

Accepted Answer

3. A Layer 3 broadcast domain corresponds to a routed IP subnet. Without a router subinterface, VLAN 99 has no Layer 3 termination, so only VLANs 10, 20, and 30 (with subinterfaces) form separate broadcast domains. Thus, there are 3 Layer 3 broadcast domains.

Answer

1

Answer

2

Answer

4

Question 5

Which of the following is a characteristic of UDP?

Accepted Answer

Has lower overhead than TCP. UDP (User Datagram Protocol) is a connectionless transport-layer protocol that provides minimal overhead compared to TCP. It does not establish a connection before sending data, nor does it provide reliability, flow control, or error recovery, making it ideal for real-time applications like VoIP and streaming where speed is prioritized over guaranteed delivery.

Answer

Provides guaranteed delivery

Answer

Uses sequence numbers

Answer

Supports three-way handshake

Question 6

A network engineer is troubleshooting connectivity issues between two data center switches that are configured to support jumbo frames with an MTU of 9000. The link is a 10 Gigabit Ethernet fiber connection. Large file transfers fail, but small transfers succeed. What is the most likely cause?

Accepted Answer

C. The most likely cause is that an intermediate device (such as a router or another switch) along the Layer 2 path is not configured for jumbo frames and has a standard MTU of 1500. Since both end switches support an MTU of 9000, large frames are sent but are dropped when they reach the intermediate device that cannot handle them. Small frames (≤1500 bytes) pass through successfully because they fit within the standard MTU.

Answer

A

Answer

B

Answer

D

Question 7

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.

Answer

802.3af

Answer

802.1D

Answer

802.11ac

Question 8

A user can access a website by its IP address (e.g., 203.0.113.5) but cannot access it by its domain name (example.com). Other users on the same subnet can access the website by domain name. Which of the following should the technician check FIRST?

Accepted Answer

Check the local hosts file. The issue is isolated to a single user who can reach the website by IP but not by domain name, while other users on the same subnet have no problem. This indicates a client-side DNS resolution problem. The first thing to check is the local hosts file (e.g., C:\Windows\System32\drivers\etc\hosts) for any incorrect or outdated entries that might be overriding DNS resolution. If the hosts file has an incorrect mapping for example.com, the browser will use that instead of querying the DNS server, causing the failure. Checking DNS server configuration is appropriate if the hosts file is clean.

Answer

Check the DNS server configuration on the network

Answer

Check the website's DNS records

Answer

Check the user's browser proxy settings

Question 9

A network engineer wants to segment a LAN into multiple broadcast domains without purchasing additional hardware. Which of the following technologies should be implemented?

Accepted Answer

VLANs. VLANs (Virtual Local Area Networks) allow a network engineer to logically segment a single physical LAN switch into multiple isolated broadcast domains without purchasing additional hardware. By assigning switch ports to different VLAN IDs, broadcast traffic is confined to ports within the same VLAN, effectively creating separate Layer 2 networks on the same switch infrastructure.

Answer

Subnetting

Answer

VPN

Answer

NAT

Question 10

A network engineer is reviewing RFC 1918 address ranges to plan a private IP addressing scheme. Which of the following IP addresses falls within the private address space for Class A?

Accepted Answer

10.10.10.1. RFC 1918 defines the Class A private address range as 10.0.0.0/8, which includes all addresses from 10.0.0.0 to 10.255.255.255. 10.10.10.1 falls within this range, making it a valid private IP address for internal network use.

Answer

172.16.0.1

Answer

192.168.1.1

Answer

172.32.0.1

Question 11

A network administrator needs to ensure high availability for a critical server that has two network interfaces connected to two different switches. Which configuration should be implemented to provide failover and load balancing at the network layer?

Accepted Answer

Link aggregation (LACP). Link Aggregation (LACP) allows multiple physical network interfaces to be combined into a single logical link, providing both failover and load balancing at Layer 2. In this scenario, the server's two NICs are connected to two different switches; LACP can be configured across the two switches (if they support Multi-chassis Link Aggregation) or the NICs can be set up in an active/standby team for failover. This satisfies the requirement for high availability and load balancing at the network layer (Layer 2/3 boundary). Virtual IP protocols like VRRP/HSRP are designed for gateway redundancy, not for server NIC failover.

Answer

Virtual IP (VRRP/HSRP)

Answer

Spanning Tree Protocol (STP)

Answer

Port mirroring

Question 12

A switch port is configured as a trunk with native VLAN 99. When a frame tagged with VLAN 99 is received on the trunk, the switch displays an error. What is the most likely issue?

Accepted Answer

The remote switch is tagging frames on the native VLAN. The native VLAN is the VLAN that carries untagged traffic on an 802.1Q trunk. By design, frames belonging to the native VLAN should be sent untagged. When a switch receives a frame tagged with the native VLAN ID (VLAN 99), it indicates a mismatch in native VLAN configuration between the two ends of the trunk. The switch logs an error because it expects native VLAN frames to be untagged, but the remote switch is incorrectly tagging them.

Answer

The trunk is using 802.1Q encapsulation and the remote switch expects ISL

Answer

The remote switch is sending frames on VLAN 99 as untagged

Answer

The allowed VLAN list does not include VLAN 99

Question 13

A network administrator has just connected a new access switch to the core switch via a trunk port. The administrator configured the trunk port on both switches with the same allowed VLAN list. However, hosts on VLAN 10 connected to the new access switch cannot communicate with hosts on VLAN 10 on the core switch. The trunk is operational and shows up/up. What is the most likely cause?

Accepted Answer

A) VLAN 10 has not been created on the new access switch. The most likely cause is that VLAN 10 has not been created on the new access switch. Even though the trunk port is up/up and the allowed VLAN list matches, a switch will not forward traffic for a VLAN that does not exist in its local VLAN database. Without the VLAN being created, the switch drops all frames tagged with VLAN 10, preventing communication between hosts on that VLAN across the trunk.

Answer

B) Native VLAN mismatch on the trunk

Answer

C) Trunk encapsulation mismatch (ISL vs 802.1Q)

Answer

D) STP is blocking the VLAN 10 traffic on the trunk

Question 14

A network administrator is preparing to upgrade the firmware on a critical router. Which document should the administrator consult to understand the steps required to minimize downtime and ensure a successful upgrade?

Accepted Answer

Change management plan. The change management plan documents the approved procedures, rollback steps, and communication protocols for performing maintenance on critical infrastructure. Consulting this plan ensures the administrator follows the organization's predefined steps to minimize downtime and mitigate risks during the firmware upgrade.

Answer

SLA

Answer

Network diagram

Answer

Baseline performance report

Question 15

After replacing a faulty network cable, a user reports that they can access local resources but not the internet. The technician verifies that the user's IP address is 192.168.1.100 with a subnet mask of 255.255.255.0 and a default gateway of 192.168.1.1. The technician can ping the default gateway successfully. Which of the following should the technician check NEXT?

Accepted Answer

A) DNS configuration. The user can access local resources and successfully ping the default gateway, which confirms that Layer 2 and Layer 3 connectivity to the local network is working. The inability to access the internet while local access works points to a name resolution failure, as the browser relies on DNS to translate domain names to IP addresses. Checking DNS configuration is the logical next step because a misconfigured or missing DNS server would prevent internet access even when IP connectivity is intact.

Answer

B) DHCP server

Answer

C) Router's firewall ACLs

Answer

D) Switch port VLAN assignment

Question 16

Users in VLAN 10 cannot obtain IP addresses from the DHCP server located in VLAN 20. The router interface for VLAN 10 has an ip helper-address 192.168.20.5 command configured, and users can ping the DHCP server IP (192.168.20.5) from the router. However, users receive APIPA addresses. What is the most likely cause?

Accepted Answer

The DHCP server does not have a scope configured for the 192.168.1.0/24 subnet (VLAN 10). The ip helper-address command on the router correctly forwards DHCPDISCOVER broadcasts from VLAN 10 to the DHCP server at 192.168.20.5. Since users can ping the server from the router, Layer 3 connectivity exists. However, the DHCP server must have a scope (or address pool) for the subnet of the requesting clients (192.168.1.0/24) to offer an IP address; without it, the server ignores the request, and clients fall back to APIPA (169.254.x.x).

Answer

The router's ip helper-address is configured on the wrong interface

Answer

The switch port connecting users is configured as a trunk instead of an access port

Answer

The router's ACL is blocking DHCP offers from the server

Question 17

A user reports that they cannot access the internet, but they can access local resources on the same subnet. The network administrator pings the default gateway and gets a response. Which tool should be used next to trace the path to an external website?

Accepted Answer

traceroute. B is correct because traceroute (tracert on Windows) is the appropriate tool to identify where packets are being dropped or delayed along the path from the local host to an external website. Since the user can access local resources and the default gateway responds to pings, the issue likely lies beyond the gateway, and traceroute will reveal the hop where connectivity fails.

Answer

netstat

Answer

nslookup

Answer

arp

Question 18

A security analyst observes that an internal server is sending a large volume of TCP SYN packets to various external IP addresses, but never completing the three-way handshake. This behavior is indicative of which type of attack?

Accepted Answer

SYN flood attack. A SYN flood attack occurs when an attacker sends a high volume of TCP SYN packets to a target but never completes the three-way handshake by sending the final ACK. This leaves the target's connection table half-open, consuming resources and potentially exhausting its ability to accept legitimate connections. The observed behavior—internal server sending many SYN packets without completing the handshake—matches the classic signature of a SYN flood, though typically the attacker spoofs the source IP to avoid response traffic.

Answer

Man-in-the-middle attack

Answer

DDoS amplification attack

Answer

Smurf attack

Question 19

A user reports that they can access the company's internal web server by IP address (10.10.10.100) but cannot access it by its hostname (intranet.company.com). The user's workstation is configured with the correct internal DNS server address. Which of the following should the technician do FIRST?

Accepted Answer

Check the DNS server's A record for intranet.company.com. The user can reach the server by IP but not by hostname, which indicates a DNS resolution problem. Since the workstation is configured with the correct internal DNS server, the most likely cause is a missing or incorrect A record for intranet.company.com on that DNS server. Checking the A record is the logical first step before other troubleshooting.

Answer

Review the firewall rules on the server

Answer

Run ipconfig /flushdns on the workstation

Answer

Verify the default gateway configuration

Question 20

A network technician notices that a switch port connected to a user's computer is showing a high number of CRC errors and late collisions. The link is operating at 100 Mbps, full duplex according to the switch. Which of the following is the most likely cause of these errors?

Accepted Answer

Duplex mismatch. CRC errors and late collisions in a full-duplex link are classic symptoms of a duplex mismatch. When one side is set to full duplex and the other to half duplex, the half-duplex side does not sense the carrier before transmitting, leading to collisions that are detected late in the frame. The switch reports full duplex, so the user's NIC is likely stuck at half duplex, causing these errors.

Answer

Cable length exceeds 100 meters

Answer

Faulty switch port

Answer

Electromagnetic interference