JN0-351 Exam Dumps : Enterprise Routing and Switching Specialist (JNCIS-ENT)

MAC limiting protects against flooding of the Ethernet switching table (also known as the MAC forwarding table or Layer 2 forwarding table). This feature is enabled on interfaces (ports). MAC limiting sets a limit on the number of MAC addresses that can be learned on a single Layer 2 access port. The MAC limit value in the EX-series switch’s default configuration is five MAC addresses. You can configure the MAC limit on an interface, on an interface in a VLAN, or on all interfaces. You can also specify the action to be taken when the MAC limit is exceeded, such as dropping packets, logging messages, or shutting down the interface. Additionally, you can configure specific “allowed” MAC addresses for the access port. Any MAC address that is not in the list of configured addresses is not learned. Allowed MAC binds MAC addresses to a VLAN so that the address does not get registered outside the VLAN. References:

[EX] How to control MAC address access through Junos OS for EX Series switches1

Configuring MAC Limiting2

Understanding MAC Limiting and MAC Move Limiting3

According to the Juniper documentation1, a native VLAN is a VLAN that carries untagged traffic on a trunk port. A Wi-Fi access point may need a native VLAN to associate untagged traffic with a specific VLAN, such as the management VLAN. On Juniper EX Series switches, you can enable a native VLAN on a switch port by setting the interface-mode to trunk and specifying a native-vlan-id. For example, the following configuration enables a native VLAN with ID 1 on the switch port ge-0/0/12:

set interfaces ge-0/0/1 unit 0 family ethernet-switching interface-mode trunk

set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan members all

set interfaces ge-0/0/1 unit 0 family ethernet-switching native-vlan-id 1

The other options are not correct because they do not address the requirement of untagged traffic. VLAN tagging is the process of adding a VLAN identifier to a frame, which is not needed for untagged traffic. Flexible VLAN tagging is a feature that allows multiple VLAN tags on a single interface, which is not relevant for this scenario. Voice VLAN is a feature that allows voice traffic to be separated from data traffic on a switch port, which is not related to untagged traffic or Wi-Fi access points. References: Understanding Native VLANs on Trunks | Junos OS, Configuring a Native VLAN on a Trunk Port | Junos OS