Juniper Enterprise Routing and Switching - Professional (JNCIP-ENT) JN0-650 Exam Dumps: Updated Questions & Answers (February 2026)

In standard BGP operations, a router typically selects only one "best path" for a given destination prefix and installs that single path into the forwarding table. To utilize multiple paths for traffic forwarding (load-balancing), specific multipath features must be enabled.

BGP Multipath: This feature allows a router to install multiple equal-cost paths into the routing and forwarding tables. However, by default, BGP multipath requires that all candidate paths have the same neighboring Autonomous System (AS).

Multipath Multiple-AS (Option B): In the exhibit, R1 is receiving routes from ISP A (AS 65501) and ISP B (AS 65502). Since these are two different neighboring ASs, the standard multipath feature is not sufficient. You must use the multipath multiple-as statement under the BGP group or neighbor hierarchy. This tells Junos to consider paths as equal even if they originate from different neighboring ASs, provided all other BGP path selection attributes (Local Preference, AS Path length, Origin, MED, etc.) are identical.

Why other options are incorrect: * Option A (multihop) is used for peering with routers that are not directly connected.

Option C (prefix limit) is a security and stability feature to limit the number of prefixes received from a neighbor.

Option D (damping) is used to penalize unstable, "flapping" routes to prevent constant routing table churn.

Configuration Example for Junos OS 24.4: To implement this on R1, you would use the following configuration:

set protocols bgp group multipath multiple-as

OSPF stub areas are used to reduce the size of the Link-State Database (LSDB) in routers with limited resources by restricting the flooding of external routes.

Virtual Links (Option C): According to OSPF standards (both v2 and v3), virtual links cannot pass through stub areas. A virtual link must transit a "transit area," which must be a standard (non-stub) area with a full routing table.

Totally Stubby Areas (Option D): A stub area (which blocks Type 5 External LSAs) can be further restricted into a totally stubby area. In Junos OS, this is done by adding the no-summaries statement to the stub configuration. This blocks both Type 5 and Type 3 (Inter-area) LSAs, replacing them with a single default route.

Incorrect Statements: Option A is incorrect because standard stub areas cannot contain an ASBR; only Not-So-Stubby Areas (NSSA) allow for an ASBR. Option B is incorrect because an area is either a Stub or an NSSA; they are mutually exclusive configurations for the same area.

In Junos OS 24.4, the no-loss forwarding class is used for traffic that requires lossless delivery, such as iSCSI or FCoE, typically in a Data Center Bridging (DCB) environment.

Priority-Based Flow Control (Option C): To guarantee "no-loss" behavior, the switch must support and use Priority-based Flow Control (PFC). PFC allows the switch to send "pause" frames for a specific priority (forwarding class) to prevent buffer overflow and packet drops without affecting other traffic on the same link.

Forwarding Class Sets (Option B): In enhanced Layer 2 software (ELS) versions used by modern QFX and EX series switches, lossless traffic must be managed within forwarding class sets (also known as priority groups). This grouping is necessary to apply specific DCB properties, such as PFC and specific bandwidth guarantees, to the lossless traffic class.

Why A and D are incorrect: Default scheduler maps and default drop profiles do not provide the specialized buffer management or lossless signaling required for this class. Lossless traffic specifically requires the suppression of tail drops rather than standard drop profiles.

The exhibit illustrates a standard end-to-end Class of Service (CoS) path consisting of an edge router (R1) and core/intermediate routers (R2 and R3).

Edge Classification (Option B): The scenario specifies that video traffic enters the network without any class-of-service markings. Because there are no DSCP or 802.1p bits to inspect, the ingress router (R1) cannot use simple Behavior Aggregate (BA) classification. Instead, it must use Multifield (MF) classification. MF classification allows the router to look deeper into the packet (Source/Destination IP, Protocol, Port numbers) to identify the video stream and assign it to a specific forwarding class. * Core Classification (Option D): Once R1 has identified the traffic, it will typically apply a rewrite rule on its egress interface to mark the packets with a specific CoS value (like a DSCP code). Consequently, the downstream routers (R2 and R3) do not need to perform expensive deep-packet inspection again. They can use Behavior Aggregate (BA) classification, which simply looks at the markings in the packet header to determine the appropriate forwarding priority.

Option A and C: These are incorrect because BA classification is impossible on unmarked ingress traffic, and performing MF classification in the core is inefficient and not a recommended Juniper design practice for high-speed transit.

The exhibit displays the default-switch.evpn.0 routing table, which is used on Juniper leaf devices to store EVPN Type 2 (MAC/IP) routes.

Route Distinguisher (Option C): In EVPN, the Route Distinguisher (RD) is an 8-byte prefix added to a route to make it unique within the BGP control plane. The RD format in the exhibit is :.

For example, the prefix 2:192.168.100.1:1::5010::... indicates an EVPN Type 2 route (2:) where 192.168.100.1:1 is the Route Distinguisher.

This RD identifies the specific routing instance on the originating VTEP that advertised the MAC/IP address.

Option A is incorrect: The RD 192.168.100.2:1 does not necessarily mean the host device has that IP; it means the originating switch has that router ID/IP used for its RD.

Option B is incorrect: While the RD often incorporates the router ID, the RD itself is the full string (e.g., 192.168.100.1:1), which is distinct from the raw Router ID used in the BGP summary.

Option D is incorrect: Looking at the entries for 10.1.1.1 and 10.1.2.3, they are associated with different identifiers in the RD strings (5010 and 5020 respectively), which typically map to different VNIs or bridge domains.

In this scenario, the requirement is to authenticate devices based on their MAC addresses using a centralized database.

MAC RADIUS (Option A): This is the standard Juniper method for authenticating "headless" or non-802.1X capable devices based on their hardware (MAC) address. The switch acts as a proxy, sending the device's MAC address as the username and password to a centralized RADIUS server (the centralized database). If the MAC address is found in the server's database, the device is granted access to the network. This perfectly matches the user's requirement for MAC-based authentication and a centralized database.

Captive Portal (Option B): This is a web-based authentication method requiring user interaction (login via a browser), which is not based on MAC address identification for the initial authentication phase.

Supplicant Modes (Options C & D): These define how multiple devices are handled on an 802.1X-enabled port, but they are not authentication methods themselves; they rely on 802.1X (EAP-based) or MAC-RADIUS being already configured.

The exhibit shows router1 (AS 65001) connected to router2 (AS 65002) via two parallel physical links. The show bgp summary output indicates that sessions are established with two neighbors: 10.10.10.1 and 10.10.20.1. Currently, for the second neighbor (10.10.20.1), there are 0 active routes despite having 4 accepted routes, which indicates that BGP has selected only one "best path" via the first neighbor for forwarding.

BGP Best Path Selection: By default, BGP only selects a single best path for any given destination prefix and installs that one path into the forwarding table. In a topology with parallel links to the same AS, this leads to underutilization of available bandwidth.

Multipath Solution (Option B): To enable active routes from both peers and allow for load-balancing (ECMP) across both links, you must enable the multipath feature.

When the multipath statement is configured under the protocols bgp group ext-peers hierarchy, it tells Junos OS to install multiple equal-cost BGP paths into the routing table and subsequent forwarding table.

Since both neighbors belong to the same peer group (ext-peers) and the same AS (65002), configuring multipath at the group level will apply to both sessions, allowing paths from both neighbors to be marked as "active".

Incorrect Options:

Option A: 172.16.1.1 is the loopback address of router2. The exhibit shows peering is currently done using physical interface addresses (10.10.10.1 and 10.10.20.1), so this address is irrelevant to the current active sessions.

Option C: Configuring the neighbor address alone without the multipath parameter will not change the best-path selection behavior.

Option D: 10.10.20.2 is the local interface IP of router1, not the neighbor's IP. BGP multipath must be configured to point to remote peer paths.

Configuration Example for Junos OS 24.4: To implement this, apply the following command: set protocols bgp group ext-peers multipath

In an EVPN-VXLAN architecture, the interaction between the control plane (EVPN) and the data plane (VXLAN) is defined by specific functional components:

VTEP (VXLAN Tunnel End Point): These are the entities responsible for the encapsulation and de-encapsulation of Layer 2 Ethernet frames into Layer 3 UDP/IP packets. A VTEP can be a physical switch (like a QFX or EX series) or a software-based entity. When traffic enters the fabric, the ingress VTEP wraps it in a VXLAN header; the egress VTEP removes this header before delivering it to the destination host. (Option B)

VNI (Virtual Network Identifier): The VNI is a 24-bit field in the VXLAN header that allows for up to 16 million unique identifiers. It is used to identify specific broadcast domains (or VLANs) within the overlay network. Each VNI effectively represents a virtualized Layer 2 segment that is stretched across the Layer 3 underlay. (Option D)

Incorrect statements: Option A is incorrect because VNIs are identifiers, not the "engine" that performs encapsulation—that is the VTEP's job. Option C is incorrect because VTEPs identify the endpoints of a tunnel, not the individual broadcast domains themselves.

The exhibit shows the MSTP configuration for two switches, switch1 and switch2. MSTP allows you to group multiple VLANs into a single Multiple Spanning Tree Instance (MSTI), enabling different root bridges and topologies for different sets of VLANs.

Root Bridge Election (Option B): For any Spanning Tree instance, the switch with the lowest bridge priority is elected as the root bridge.

For msti 2, switch1 has a priority of 4k (4096), while switch2 has a priority of 8k (8192).

Since 4096 < 8192, switch1 is elected the root bridge for msti 2.

Failover Behavior (Option D): Spanning Tree is designed for redundancy. If a primary root bridge fails, the remaining switches in the network re-elect a new root based on the next lowest priority.

If switch2 goes down, switch1 becomes the only switch in the region.

Regardless of its original priority (4k or 8k), switch1 will take over as the root bridge for both msti 1 and msti 2 because there are no other contenders with a better (lower) priority.

Incorrect Statements: Option A is incorrect because for msti 1, switch2 has the lower priority (4k vs. 8k), making switch2 the root bridge. Option C is incorrect because it contradicts the fundamental high-availability nature of Spanning Tree.

This scenario describes a specific use case where a switch port is shared by multiple devices (e.g., via a downstream unmanaged switch), and you want to simplify the authentication process.

Single Supplicant Mode (Option A): In this mode, the switch requires only the first device that connects to the port to successfully authenticate via 802.1X. Once that first device is authorized, the switch "opens" the port for all traffic. This means all subsequent devices attached to that same downstream switch are permitted to access the network without undergoing their own authentication.

Other Modes:

Single-secure supplicant (C): Only allows the first authenticated device; all others are blocked.

Multiple supplicant (D): Requires every device to authenticate individually.

MAC RADIUS (B): This is an authentication method, not a port-control mode.