Complete N10-009 CompTIA Materials

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.

The correct answer is ACL (Access Control List). According to the CompTIA Network+ N10-009 objectives, ACLs are a fundamental and cost-effective method for controlling traffic flow at routers and firewalls. An ACL allows administrators to permit or deny traffic based on source IP address, destination IP address, protocol, or port number.

In this scenario, the suspicious traffic is identified as originating from a specific unknown foreign IP address. The most direct and economical mitigation strategy is to configure an ACL rule that denies traffic from that specific IP address (or subnet) at the network perimeter. This approach leverages existing network infrastructure without requiring additional hardware or licensing costs.

An IDS (Intrusion Detection System) monitors and alerts on malicious activity but does not actively block traffic unless paired with IPS functionality, and it may involve additional cost and complexity. NAT is used for address translation and does not provide traffic filtering based on threat intelligence. DoS prevention solutions are typically more advanced, specialized, and costly, often intended for large-scale distributed denial-of-service attacks rather than blocking traffic from a single suspicious IP.

The Network+ objectives emphasize implementing layered security controls, starting with simple and effective measures. In this case, applying an ACL at the firewall or router is the most cost-efficient and immediate method to mitigate the identified threat.

The correct answer is A. Multicast. In IPv4 addressing, Class D refers to the address range 224.0.0.0 through 239.255.255.255, and that range is reserved specifically for multicast traffic. Multicast allows one sender to communicate with a group of receivers that have joined a particular multicast address.

This differs from the other traffic types. Unicast is one source to one destination. Broadcast is sent to all hosts on the local network segment. Anycast is not represented by the IPv4 Class D block and instead refers to sending traffic to the nearest member of a group using the same address. Therefore, the only traffic type directly associated with Class D space is multicast.

This is a straightforward address-class recognition concept that appears frequently in Network+ preparation. Once a student remembers that Class D equals multicast, these questions become much easier to answer. Multicast is useful for applications such as video streams, routing protocol updates, and other scenarios where data must reach multiple selected hosts efficiently without sending separate unicast copies to each one. That is why the correct answer is multicast.

SSO (Single Sign-On) allows an organization to use an identity provider (IdP) to centrally manage authentication and access across multiple SaaS applications. In the Network+ (N10-009) objectives, identity and access management concepts include federated authentication, centralized account control, and reducing password sprawl. With SSO, users authenticate once to the IdP, and the IdP then provides assertions/tokens to SaaS services (commonly using federation standards such as SAML or OIDC in real environments). This improves security (fewer reused passwords, easier MFA enforcement), streamlines user experience, and simplifies administration (provisioning/deprovisioning from one place).

PKI supports certificates and encryption/signing, but it is not the core mechanism for managing access across many SaaS apps via an IdP. TACACS+ is typically used for device administration (AAA) on network equipment, and RADIUS commonly supports network access (802.1X, VPN) AAA—both are important AAA protocols but do not describe the SaaS-wide “one login across many apps” capability. Therefore, SSO is the best answer.

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