Most Recent Juniper JN0-352 Exam Dumps

Voice VLAN is the Junos feature specifically designed to allow a single access port to simultaneously handle two distinct traffic streams: untagged data traffic from a PC or workstation using the port's normal access VLAN, and separately tagged voice traffic generated by an IP telephone that is typically daisy-chained between the switch port and the connected PC. When voice VLAN is configured on an access interface, the switch instructs the attached IP phone (commonly via LLDP-MED) which VLAN ID to tag its voice traffic with, and the switch is then able to correctly classify and prioritize that tagged voice traffic into its designated voice VLAN while simultaneously continuing to treat any untagged frames arriving on that same physical port as belonging to the port's regular, untagged access VLAN --- precisely satisfying the requirement to accept both tagged and untagged traffic together on one access port. Native VLAN, by contrast, is a trunk-port-only concept that designates which VLAN untagged frames on a trunk should be associated with; it has no applicability to an access port and does not enable simultaneous tagged traffic acceptance there. Default VLAN simply refers to the VLAN an interface belongs to absent other configuration and carries no dual-traffic capability. IRB interfaces provide Layer 3 gateway functionality for a VLAN and are unrelated to how tagged versus untagged frames are accepted at Layer 2 on a given physical port. Reference topics: Junos Enterprise Switching -- VLANs, Configuring Voice VLAN on Access Interfaces.

Because root bridge election is decided primarily by comparing bridge priority values --- with the switch advertising the numerically lowest priority always winning, and MAC address serving only as a fallback tiebreaker when priorities are tied --- the only deterministic, reliable way to guarantee that a specific switch is elected root regardless of any other switch's hardware characteristics is to explicitly configure that switch with a lower bridge priority than every other participating switch in the topology. Relying on MAC address alone, as the first distractor suggests, is fundamentally unreliable: MAC addresses are burned in at the factory, cannot be predicted or controlled by the administrator, and any future hardware replacement or newly introduced switch with a numerically lower MAC address could unexpectedly seize the root role since MAC comparison only comes into play at equal priority in the first place, meaning a 'highest MAC' strategy does not even align with how the tiebreak actually favors the lowest value. Port priority and port cost are entirely separate STP parameters that influence which port on a non-root switch is selected as its root port, or which port is selected as designated versus blocking on a given segment; neither parameter has any bearing whatsoever on which switch is elected root bridge for the whole topology, since that decision is made purely from the Bridge ID comparison, independent of any per-port settings. Explicitly and deliberately lowering Switch 1's configured bridge priority is the only correct, industry-standard method. Reference topics: Junos Enterprise Switching -- Spanning Tree Protocols, Guaranteeing Root Bridge Placement via Bridge Priority.

TLV 22, the Extended IS Reachability TLV defined in RFC 5305, is the modern and Junos-preferred mechanism for advertising a router's adjacent neighbors together with the metric associated with each link. It carries the seven-octet system ID and pseudonode number of each neighbor along with a 24-bit wide metric field, and supports an extensible set of sub-TLVs used for traffic-engineering data such as interface and neighbor IP addresses, bandwidth, and administrative groups. The original IS Reachability TLV, TLV 2, defined in the base ISO 10589 standard, carries similar neighbor and metric information but is constrained to a 6-bit narrow metric with a maximum value of 63, which is inadequate for expressing meaningful cost differentiation in modern, high-capacity enterprise and service-provider topologies; consequently, Junos deployments are commonly configured for wide-metrics-only, favoring TLV 22 over the legacy TLV 2 whenever traffic-engineering-capable or simply more granular metric representation is desired. TLV 132, the IP Interface Address TLV, only advertises the IPv4 addresses configured on the originating router's interfaces and carries no neighbor-adjacency or metric information. TLV 129, the Protocols Supported TLV, merely lists which network-layer protocols (such as IPv4 or IPv6) the originating router is capable of routing, and likewise has nothing to do with neighbor reachability or link cost. Reference topics: Junos Enterprise Routing -- IS-IS, Extended IS Reachability and Wide Metrics.

Root bridge election is based on comparing each switch's full Bridge Identifier, which combines the bridge priority value with the switch's MAC address, with priority always evaluated first and MAC address serving strictly as a tiebreaker when two or more switches present identical priority values. In this scenario, the network has been left entirely at the default spanning-tree configuration, meaning every switch is operating at the standard IEEE and Junos default bridge priority of 32768; since all three switches share the exact same priority value, the comparison necessarily falls through to the MAC address tiebreak, where the switch with the numerically lowest MAC address wins the election. Comparing the three addresses shown --- 00:1a:2b:3c:4d:01, 00:1a:2b:3c:4d:02, and 00:1a:2b:3c:4d:03 --- Switch A's address is the lowest, since only the final octet differs and 01 is less than both 02 and 03, making Switch A the elected root bridge. RSTP uses the identical Bridge ID comparison mechanism as legacy STP for root election, so there is no special 'median MAC address' rule that applies uniquely under RSTP, making that distractor factually invalid regardless of protocol version. The election process also does not require any manual bridge priority configuration to complete; the default priority value is entirely sufficient on its own to allow a deterministic election to occur, since default priorities are still numerically comparable Bridge IDs. Reference topics: Junos Enterprise Switching -- Spanning Tree Protocols, Default Priority and MAC Address Tiebreaking.

IEEE 802.3ad LACP defines two distinct negotiation modes, active and passive, and the standard's fundamental requirement for successful negotiation is that at least one end of the point-to-point link must be configured in active mode; an actively configured device initiates LACPDU transmission on its own, while a passively configured device waits and only responds once it receives an LACPDU from its peer. If both ends of the bundle were left in passive mode simultaneously, neither side would ever initiate the exchange, and no negotiation --- and therefore no functioning aggregated bundle --- would ever occur; at least one active participant is therefore mandatory, though having both sides active (active-active) is also fully valid and is in fact the most common production deployment. Junos does not enable LACP automatically on aggregated Ethernet interfaces; unlike some competing platforms, LACP must be explicitly configured under the aggregated-ether-options lacp hierarchy, and specifying no LACP configuration at all results in a 'static' LAG that relies purely on physical link-state rather than any protocol negotiation --- there is no implicit default active mode. There is likewise no requirement to configure differing LACP system priority values between the two peer switches; system priority is used only to determine which side of the link controls port selection during negotiation and has no bearing on whether the bundle can form. Both sides being mandatorily active is a stricter requirement than the actual standard specifies. Reference topics: Junos Enterprise Switching -- Link Aggregation, LACP Active and Passive Mode Negotiation.