N10-009 Practice Test 33 — 15 Questions

Question 1

Users in a conference room frequently experience slow and dropping wireless connections. A site survey shows three other access points in the vicinity all using channel 6. Signal strength is adequate. What is the most likely cause?

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

Accepted Answer

Co-channel interference. All three nearby access points are operating on channel 6, which causes co-channel interference. Even with adequate signal strength, overlapping basic service sets (BSSs) on the same channel lead to contention, increased collisions, and reduced throughput due to the CSMA/CA mechanism in 802.11 networks. This results in slow and dropping connections for users in the conference room.

Answer

Incorrect encryption settings

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Incorrect SSID configured

Answer

Low antenna gain on the access points

Question 2

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.

Answer

802.11ac (Wi-Fi 5)

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802.11n (Wi-Fi 4)

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802.11g (Wi-Fi 3)

Question 3

A network administrator needs to connect two switches to allow multiple VLANs to traverse the link. Which protocol should be used to tag frames with VLAN information?

Accepted Answer

802.1Q. 802.1Q is the IEEE standard for VLAN tagging, which inserts a 4-byte tag into the Ethernet frame header to identify the VLAN membership of the frame. This allows multiple VLANs to traverse a single trunk link between switches, enabling inter-switch VLAN communication without requiring separate physical links per VLAN.

Answer

STP (Spanning Tree Protocol)

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VTP (VLAN Trunking Protocol)

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LACP (Link Aggregation Control Protocol)

Question 4

A network administrator needs to identify which hosts are generating the most traffic on the network and what types of traffic (e.g., HTTP, FTP). Which monitoring technology should be deployed?

Accepted Answer

NetFlow. NetFlow is the correct choice because it provides detailed visibility into network traffic flows, including source/destination IPs, ports, protocols, and application-level information (e.g., HTTP, FTP). Unlike SNMP, which only gives aggregate interface statistics, or Syslog, which logs device events, NetFlow captures per-flow metadata that directly answers the question of which hosts are generating the most traffic and what types of traffic they are using.

Answer

SNMP

Answer

Syslog

Answer

ICMP

Question 5

A network engineer is configuring a trunk link between two switches to carry VLANs 10, 20, and 30. On Switch A, the port is configured with 'switchport mode trunk' and 'switchport nonegotiate'. On Switch B, the port is left at the default configuration. Which additional configuration is required on Switch B?

Accepted Answer

Manually set the port to trunk mode.. Switch B is left at default configuration, which on most Cisco switches means the port is in dynamic desirable or dynamic auto mode, relying on DTP to negotiate trunking. Since Switch A has 'switchport nonegotiate' configured, it will not send DTP frames, so Switch B will never receive a negotiation trigger and will remain in access mode. Therefore, the port on Switch B must be manually set to trunk mode with 'switchport mode trunk' to establish the trunk link.

Answer

Set the native VLAN to 1.

Answer

Enable DTP on Switch B.

Answer

Configure the allowed VLAN list.

Question 6

A user reports that they can access a web server by its IP address (e.g., 10.10.10.50) but cannot access it by its domain name (e.g., server.example.com). The technician verifies that the DNS server is reachable and that the name resolves correctly from other workstations on the same subnet. Which of the following should the technician check NEXT?

Accepted Answer

Check the DNS cache on the user's workstation. The user's workstation can reach the web server by IP but not by domain name, while other workstations resolve the name correctly. This strongly suggests a local DNS resolution issue specific to that workstation, such as a corrupted or stale DNS cache. Flushing the DNS cache with `ipconfig /flushdns` is the logical next step before investigating broader network or firewall issues.

Answer

Verify the default gateway configuration

Answer

Renew the DHCP lease

Answer

Disable the Windows Firewall

Question 7

A network administrator needs to implement a solution that allows for centralized management of user authentication, authorization, and accounting for network device access. The solution must support encryption of the entire authentication process. Which protocol should be selected?

Accepted Answer

TACACS+. TACACS+ is the correct choice because it separates authentication, authorization, and accounting (AAA) into distinct processes and encrypts the entire authentication payload, including the username, password, and all other traffic between the client and the server. This full-packet encryption ensures that credentials and session details are protected during transit, meeting the requirement for centralized management with encrypted authentication.

Answer

RADIUS

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LDAP

Answer

Kerberos

Question 8

A network engineer has established an IPsec VPN tunnel between a branch office (10.0.0.0/24) and the main office (192.168.10.0/24). The tunnel shows as up and active, but users at the branch office cannot ping the main office server at 192.168.10.10. The main office can ping the branch office gateway successfully. What is the most likely cause of this issue?

Accepted Answer

Incorrect static route on the branch router for the 192.168.10.0/24 network. The tunnel is up and active, and the main office can ping the branch office gateway, which confirms that Phase 1 and Phase 2 of IPsec are correctly negotiated and that the tunnel is passing traffic from the main office toward the branch. However, branch users cannot reach 192.168.10.10, indicating that return traffic from the branch is not being routed into the tunnel. The most likely cause is that the branch router lacks a static route for 192.168.10.0/24 pointing to the tunnel interface (or the IPsec virtual interface), so packets from the branch destined for the main office are sent out the wrong interface or dropped instead of being encrypted and forwarded through the VPN.

Answer

Mismatched encryption algorithms between the two VPN peers

Answer

Firewall on the main office server blocking ICMP

Answer

Incorrect IKE authentication settings

Question 9

A network technician is assigned a subnet mask of 255.255.255.248. How many usable host addresses are available in this subnet?

Accepted Answer

A) 6. The subnet mask 255.255.255.248 corresponds to a /29 prefix length, which provides 2^(32-29) = 8 total addresses. Subtracting the network address and broadcast address leaves 8 - 2 = 6 usable host addresses.

Answer

B) 8

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C) 14

Answer

D) 30

Question 10

A network engineer plans to change the routing protocol configuration on a core router that will affect connectivity to all branches. According to change management best practices, which step should the engineer perform BEFORE implementing the change?

Accepted Answer

Create a backout plan to revert the change if necessary. Creating a backout plan is a critical step in change management because it provides a documented procedure to revert the router to its previous operational state if the new routing protocol configuration causes connectivity loss or instability. Without a backout plan, the engineer risks prolonged outages across all branches while troubleshooting or attempting to reconstruct the original configuration from memory or incomplete logs. This aligns with ITIL change management best practices, which prioritize risk mitigation and service continuity.

Answer

Notify all branch users of the upcoming change

Answer

Document the current router configuration

Answer

Schedule the change during a maintenance window

Question 11

Two switches are connected via a trunk link configured with allowed VLANs 10, 20, and 30. Hosts on VLAN 20 can communicate across the trunk, but hosts on VLAN 30 cannot. Which of the following is the most likely cause?

Accepted Answer

D. The most likely cause is that VLAN 30 is only created on one switch. For a trunk to forward frames for a VLAN, that VLAN must exist (be created) on both switches. If VLAN 30 is only configured on one switch, the other switch will drop frames from VLAN 30, preventing communication. This explains why VLAN 20 works (exists on both) and VLAN 30 does not.

Answer

A

Answer

B

Answer

C

Question 12

A company has just installed a new fiber optic connection between two buildings 2 km apart. The connection is using multimode fiber. However, the signal is too weak at the receiving end. What is the most likely cause?

Accepted Answer

Attenuation due to distance. Multimode fiber (MMF) is designed for shorter distances, typically up to 550 meters for 10 Gbps (OM3/OM4) and up to 2 km only for lower speeds like 100 Mbps or 1 Gbps using older OM1/OM2 fiber. At 2 km, the signal attenuation exceeds the power budget of the MMF link, causing a weak signal at the receiver. Single-mode fiber (SMF) would be required for reliable transmission over this distance.

Answer

Electromagnetic interference

Answer

Incorrect termination

Answer

Crosstalk

Question 13

A network engineer has configured an IPsec site-to-site VPN between two offices. The tunnel is established and shows as active. However, users at the branch office (10.0.1.0/24) cannot reach servers at the main office (192.168.1.0/24). Both routers have the correct VPN policies and firewall rules permitting IPsec traffic. What should the engineer check next?

Accepted Answer

B) That the routing tables on both routers include routes to the remote subnet. The tunnel being active means Phase 1 and Phase 2 of IPsec are established, but traffic still cannot flow because the routers lack routes to the remote subnets. Without a route for 10.0.1.0/24 on the main office router (or 192.168.1.0/24 on the branch router), packets will be dropped or sent out the wrong interface, even though the VPN policy and firewall rules are correct. The engineer must verify that static routes or a dynamic routing protocol (e.g., OSPF over the tunnel) are in place to direct traffic into the IPsec tunnel interface.

Answer

A) That the DNS server addresses are correctly configured

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C) That the MTU size is set to 1500 on both ends

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D) That the SSID is correctly configured on the access points

Question 14

Which of the following IP addresses is a private IP address as defined by RFC 1918?

Accepted Answer

192.168.1.1. (192.168.1.1) is correct because RFC 1918 reserves the 192.168.0.0/16 block (192.168.0.0 – 192.168.255.255) for private use within local networks. This address is not routable on the public internet, making it suitable for internal LAN addressing.

Answer

169.254.1.1

Answer

172.32.1.1

Answer

172.15.1.1

Question 15

A network engineer needs to implement a wireless network in a large open-plan office with high client density. The network must provide the fastest possible speeds and efficient handling of many simultaneous connections. Which IEEE 802.11 standard should be used?

Accepted Answer

802.11ax. 802.11ax (Wi-Fi 6) is the correct choice because it introduces Orthogonal Frequency Division Multiple Access (OFDMA) and MU-MIMO (both uplink and downlink), which significantly improve spectral efficiency and capacity in high-density environments. It also supports 1024-QAM modulation for higher data rates, making it ideal for an open-plan office with many simultaneous connections.

Answer

802.11ac

Answer

802.11n

Answer

802.11r