N10-009 Exam Questions Tutorials

Link Layer Discovery Protocol (LLDP) is a network protocol used for discovering devices and their capabilities on a local area network, primarily at the data link layer (Layer 2). It helps in identifying the connected switch and the specific port to which a device is connected. When troubleshooting a VoIP handset connection, the technician can use LLDP to determine the exact switch and port where the handset is connected. This protocol is widely used in network management to facilitate the discovery of network topology and simplify troubleshooting.

Other options such as IKE (Internet Key Exchange), VLAN (Virtual LAN), and netstat (network statistics) are not suitable for identifying the switch and port information. IKE is used in setting up secure IPsec connections, VLAN is used for segmenting networks, and netstat provides information about active connections and listening ports on a host but not for discovering switch port details.

Understanding Subnetting:

The subnet mask 255.255.255.240 (or /28) indicates that each subnet has 16 IP addresses (14 usable addresses, 1 network address, and 1 broadcast address).

Calculating the Subnet Range:

Subnet Calculation: For the IP address 10.0.0.95 with a /28 subnet mask:

Network address: 10.0.0.80

Usable IP range: 10.0.0.81 to 10.0.0.94

Broadcast address: 10.0.0.95

Router Interface Configuration:

Broadcast Address Issue: The IP address 10.0.0.95 is the broadcast address for the subnet 10.0.0.80/28. Configuring a router interface with the broadcast address will cause routing issues as it is not a valid host address.

Comparison with Other Options:

The web server is in a different subnet: The web server (10.0.0.81) is within the same subnet range (10.0.0.80/28).

The IP address space is a class A network: While 10.0.0.0 is a Class A network, this does not explain the routing issue caused by the broadcast address.

The subnet is in a private address space: The private address space designation (RFC 1918) does not impact the routing issue related to the broadcast address configuration.

Resolution:

Reconfigure the router interface with a valid host IP address within the usable range, such as 10.0.0.94.

The correct answer is The port ' s VLAN assignment on the switch because the symptoms indicate a Layer 2 segmentation issue. According to CompTIA Network+ (N10-009) troubleshooting methodology and VLAN concepts, if the IP configuration is correct and the TCP/IP stack is functioning, but the default gateway is unreachable, the issue often involves improper VLAN configuration.

In a switched environment, devices must be assigned to the correct VLAN to communicate with the appropriate default gateway interface (often configured on a router or Layer 3 switch). If the user’s switch port is assigned to the wrong VLAN, the workstation may have a valid IP address but will not be able to reach the gateway because it is logically separated into a different broadcast domain.

Option A is unlikely since the IP configuration is already confirmed correct. Option C is not relevant because the issue is localized to a specific user, not a widespread DHCP failure. Option D refers to switch management configuration, which does not affect user traffic routing to the gateway.

Therefore, verifying the switch port’s VLAN assignment is the most appropriate next troubleshooting step.

Using Pre-Shared Key (PSK) authentication means that all users share the same Wi-Fi password, making it difficult to identify individual users when security incidents occur.

Migrating to WPA2-Enterprise (or WPA3-Enterprise) replaces PSK authentication with individual user credentials using 802.1X authentication and a RADIUS server. This allows the organization to:

Track and log specific user activity

Enforce per-user authentication policies

Improve network security

Breakdown of Options:

A. Restrict users to the 5GHz frequency – Improves performance but does not enhance user tracking or security.

B. Upgrade to a mesh network – A mesh network improves coverage, not security tracking.

C. Migrate from PSK to Enterprise – ✅ Correct answer. WPA2-Enterprise or WPA3-Enterprise uses individual user authentication, allowing per-user tracking.

D. Implement WPA2 encryption – WPA2 is already widely used; it does not resolve the tracking issue.