Juniper Updated JN0-352 Exam Questions and Answers by nella

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.

A floating static route is a backup static route that remains present in the configuration but stays inactive in the routing table under normal conditions, only becoming active if the primary, preferred route to the same destination is withdrawn or otherwise becomes unavailable. Junos determines which of several competing routes to the same prefix becomes active strictly by comparing each route's preference value (administrative distance), with the numerically lowest preference always winning; every routing protocol and static routes themselves carry a default preference (5 for standard static routes), and this value can be explicitly overridden per route using the preference statement under the static route's configuration. To create a floating static route, the administrator deliberately configures a preference value higher (that is, numerically worse, less preferred) than the preference of the primary route it is meant to back up — for example, a value higher than the 5 default of an ordinary static route, or higher than a dynamic protocol's preference such as OSPF's 10 — ensuring the floating route only becomes active once the more-preferred primary route disappears from the table entirely. This preference-based mechanism is the essential, defining configuration element of a floating static route. Priority is not a valid Junos static-route statement, next-hop simply defines where matching traffic is forwarded without controlling route selection behavior, and qualified-next-hop is a related but distinct mechanism used to assign a per-next-hop preference within a single multi-next-hop static route statement rather than between the standalone static route and its dynamic counterpart. Reference topics: Junos Enterprise Routing – Protocol Independent Routing, Configuring Floating Static Routes with Preference.

Layer 2 MAC learning on an EX Series switch, as on any standard Ethernet bridge, is a passive, frame-driven process rather than an active polling or query-based mechanism. Every time a frame arrives on any interface, the switch inspects the frame's source MAC address field and, if that address is not already present in the Ethernet switching (bridge) table for the associated VLAN, creates a new dynamic entry recording the source MAC address, the VLAN it was learned on, and the specific ingress interface through which the frame arrived. Junos also stamps each learned entry with an aging timestamp, which is refreshed every time a subsequent frame from that same source MAC is received; entries that receive no refreshing traffic within the configured MAC aging interval (300 seconds by default) are eventually purged from the table to keep it current and to reclaim table space from hosts that have moved or gone offline. This source-address-driven, per-frame learning process happens continuously and automatically with no dependency on spanning-tree state changes — although a topology change notification can trigger accelerated aging of the table to flush potentially stale entries faster, learning itself is not gated by or contingent upon such an event occurring. The switch never learns addresses from the destination field of a frame, since the destination address, if already known, is used purely for the forwarding lookup decision, not for populating new table entries. Reference topics: Junos Enterprise Switching – Layer 2 Switching Fundamentals, Source MAC Learning and Table Aging.

Configuring interface-type p2p under an OSPF interface tells Junos to treat that interface as a point-to-point network type regardless of the underlying physical medium, which removes the interface from the standard broadcast-network state machine entirely. On a true broadcast network, two routers must first complete a Designated Router and Backup Designated Router election, wait through the associated timers, and only then proceed through 2-Way, ExStart, Exchange, and Loading before reaching Full — a multi-step process. A point-to-point interface skips DR/BDR election altogether and proceeds directly from 2-Way into ExStart, so adjacencies form measurably faster, which is the first correct benefit. Because there is no DR on a point-to-point interface, Junos also does not generate a Type 2 Network LSA to describe the segment; the connected subnet is instead advertised as a simple stub-network entry inside the Router LSA itself, eliminating an entire LSA type from the area's link-state database and reducing its overall size, which is the second correct benefit. Point-to-point configuration is entirely incompatible with DR election, so a router configured this way cannot 'win' a DR election — there is no DR to win. Advertisement of the connected network happens on any operational OSPF interface irrespective of network type, so that option describes normal OSPF behavior rather than a benefit specific to the point-to-point setting. Reference topics: Junos Enterprise Routing – OSPF Network Types, Configuring OSPF Interface Type.