VLANs (Virtual Local Area Networks) segment network traffic by department, allowing ACLs (Access Control Lists) to be applied based on VLAN membership, improving security and resource isolation.
Breakdown of Options:
A). VLAN - Correct answer. VLANs enable logical network segmentation, allowing ACLs per department.
B). DHCP - Assigns IP addresses but does not control access.
C). VPN - Provides remote access, not segmentation within a network.
D). STP - Prevents switching loops, not related to ACL implementation.
Reference:
CompTIA Network+ (N10-009) Official Study Guide - Domain 1.3: Explain VLANs and network segmentation.
IEEE 802.1Q: VLAN tagging standard

The correct answer is BNC. A Bayonet Neill-Concelman connector, commonly called a BNC connector, is used with coaxial cable. Coaxial cabling has historically been used in Ethernet networks, cable broadband, CCTV systems, and radio frequency applications. BNC connectors use a twist-lock bayonet mechanism that provides a secure connection and helps maintain signal integrity over coaxial media.
The CompTIA Network+ N10-009 objectives include recognizing common cable types and connectors used in networking. SC and MPO are fiber-optic connectors, not coaxial connectors. SC connectors are commonly used for fiber connections and have a push-pull design. MPO connectors are multi-fiber push-on connectors often used in high-density fiber environments. RJ11 is commonly associated with telephone cabling and DSL connections, not coaxial Ethernet or RF-style network cabling. Since coaxial cable uses a central conductor, insulation, shielding, and an outer jacket, it requires connectors designed specifically for coaxial signaling.
Among the listed options, BNC is the connector type associated with transmitting network data over coaxial cable.

The correct answer is D. SVI. When traffic must move between multiple VLANs, some Layer 3 function has to exist so each VLAN can have a gateway. A Switched Virtual Interface (SVI) provides a logical Layer 3 interface for a VLAN and is commonly used to support inter-VLAN communication. In exam wording, when the question points to communication across multiple VLANs, the important idea is that each VLAN needs a Layer 3 presence.
The other answer choices do not fit this requirement. Static routing is used to define network paths, but it does not by itself create the VLAN gateway interfaces needed for inter-VLAN traffic. NAT translates addresses, usually for internet access, not for switching between local VLANs. Full duplex is a link operation mode and has nothing to do with routing traffic between VLANs.
The phrase "communicating over multiple VLANs" is the key clue. VLANs are separate broadcast domains, so devices in different VLANs cannot communicate without Layer 3 intervention. Among the choices given, SVI is the only answer that provides that Layer 3 function in a switched environment. That is why D is the best answer.

VLAN hopping allows an attacker to send traffic into another VLAN without authorization, often by impersonating a switch and negotiating a trunk link. This lets the attacker traverse into normally inaccessible VLANs.
A). MAC flooding disrupts switch operations but does not cross VLANs.
B). DNS poisoning corrupts name resolution.
D). ARP spoofing reroutes local traffic but doesn't grant VLAN traversal.
References (CompTIA Network+ N10-009):
Domain: Network Security - VLAN attacks, unauthorized lateral movement.

If a switch has port security enabled (such as sticky MAC or a configured allowed MAC), the port will only allow the original NIC's MAC address. When a new NIC with a different MAC address is installed, the port rejects traffic, preventing network connectivity.
B). BPDU guard protects against rogue switches, not end hosts.
C). Link aggregation applies when bundling multiple uplinks, not a single PC connection.
D). PoE budget applies to powered devices like APs, not PCs.
References (CompTIA Network+ N10-009):
Domain: Network Troubleshooting - Port security, MAC address filtering, switch security features.