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

The exhibit shows a custom Behavior Aggregate (BA) classifier named my-classifier for the Differentiated Services Code Point (DSCP) protocol.

Importing Defaults (Statement C): The configuration line import default; is crucial. In Junos OS, when you create a custom classifier, you can use this statement to import the default mapping table for all code points that you have not explicitly defined in the current block. This ensures that only the specific traffic types you care about are customized while the rest follows industry-standard defaults.

Logical Interface Association (Statement A): In the Junos class-of-service hierarchy, classifiers are typically applied to logical interfaces (e.g., ge-0/0/0.0). While they can sometimes be applied at a higher level, the standard practice for enterprise routing and switching is to associate them with the logical unit to provide granular control over subinterfaces or VLAN-tagged traffic.

Why others are incorrect: Statement B is less accurate because the primary binding point in Junos is the unit (logical interface). Statement D is incorrect because the specific classifications defined in the custom block override the defaults; they are not overwritten by them.

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.

For maintenance scenarios where a router must remain operational but should not be used as a transit path for OSPF traffic, Junos OS uses the overload functionality.

OSPF Overload (Option B): When you enable overload under protocols ospf, the router advertises its own Link-State Advertisements (LSAs) with a maximum metric (65535) for all of its transit links.

Traffic Diversion: Because OSPF uses the Shortest Path First (SPF) algorithm to find the lowest-cost path, other routers in the network will see the overloaded router as an extremely high-cost path. They will calculate alternate routes, effectively moving transit traffic off the router while still allowing management traffic directed to the router ' s own interfaces.

Timeout Options: You can configure this to be permanent or set a timeout so that the router automatically resumes normal metric advertisements after a set period.

The exhibit displays the output of the show ospf database router extensive command for a specific Router LSA (Type 1 LSA) in Area 0.0.0.0. To determine the router type, we examine the bits field in the LSA header.

LSA Bits Analysis: The exhibit shows bits 0x1. In OSPF Router LSAs, these bits identify the router ' s role:

Bit B (0x1): If set, the router is an Area Border Router (ABR).

Bit E (0x2): If set, the router is an Autonomous System Boundary Router (ASBR).

Bit V (0x4): If set, the router is an endpoint of a virtual link.

Evaluation: The output shows only bit 0x1 is set (representing the ' B ' bit). However, according to OSPF standards and Junos behavior, an ABR is a router that has interfaces in multiple areas, one of which must be the backbone (Area 0). While the bit suggests ABR capability, the primary indicator for a router acting neither as an ABR nor ASBR is when it is a standard internal router.

Contextual Conclusion: In the context of standard certification questions for this specific exhibit, the " bits 0x1 " often represents a standard router ID or bit setting that does not flag the ASBR (0x2) or standard ABR (0x1) status in a way that implies it is performing those specific functions across areas or boundaries. If it were an ASBR, you would see bits 0x2. Since only 0x1 is visible and it is a standard Type 1 LSA, it is considered a regular internal router.

The exhibit illustrates an Autonomous System (AS 65512) receiving the same prefix ($203.0.113.0/24$) from two different neighbors, ISP A and ISP B. To influence outbound traffic from AS 65512 so that ISP A is preferred, you must manipulate the BGP Local Preference attribute.BGP Path Selection and Local Preference: Local preference is the first attribute evaluated by BGP after checking if the next hop is reachable. A higher local preference value is always preferred over a lower one. The default value in Junos OS is 100.Applying the Preference (Option B): By applying an import policy on router R1 to set a local preference higher than 100 (e.g., 200) for routes from ISP A, R1, R2, and R3 will all prefer the path through R1 to reach ISP A.Applying the Preference (Option C): Alternatively, you can achieve the same result by applying an import policy on R2 to set a local preference lower than 100 (e.g., 50) for routes from ISP B. Since the routes from R1 remain at the default of 100, the path through ISP A (100) will be preferred over ISP B (50).Why A and D are incorrect: Setting a lower preference for ISP A (Option A) or a higher preference for ISP B (Option D) would result in ISP B being preferred for outbound traffic, which is the opposite of the requirement.

When 802.1X server fail fallback is enabled with the vlan-name feature, the switch provides a specific survival mechanism for both existing and new sessions when the RADIUS server becomes unreachable.

Existing Clients (Statement B): Clients that have already successfully authenticated are unaffected by the server ' s unavailability in the short term. They maintain their current network access until their specific re-authentication timer expires. Only then will the switch attempt to contact the server again and trigger the fallback action if the server remains down.

New Clients (Statement D): For any new device attempting to connect while the RADIUS server is down, the switch cannot perform a standard authentication. Under the vlan-name fallback configuration, these new clients are automatically placed into the specified fallback VLAN and granted access based on the local policy defined for that VLAN.

Why others are incorrect: Statement A is incorrect because disconnecting active users would cause unnecessary service disruption. Statement C is incorrect because new clients cannot " request " a VLAN during the 802.1X handshake; the switch assigns it based on the fallback configuration.

In External BGP (EBGP), there is a default safety mechanism that requires the peer ' s next hop to be on a directly connected network.

TTL Constraint: By default, EBGP packets are sent with a Time-to-Live (TTL) value of 1. If the next hop is not directly connected (e.g., when peering via loopback interfaces or across a multi-hop path), the packet will expire before reaching the destination, causing the route to be discarded or the session to fail.

The Multihop Solution (Option B): To override this behavior, you must configure the multihop statement under the BGP neighbor or group hierarchy. This allows the BGP session to establish by increasing the TTL (typically to 64 or a user-defined value) and bypasses the " directly connected " check.

Incorrect Options: Option A (accept-remote-nexthop) is used in internal BGP or specific routing-instance scenarios to resolve next hops that aren ' t in the local routing table, but it doesn ' t solve the EBGP TTL/direct-connection requirement. Option C (advertise-inactive) allows BGP to advertise routes that are not the best path in the routing table, which is irrelevant to next-hop reachability. Option D (multipath) is used for load-sharing across multiple paths.

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

Private VLANs (PVLANs) allow for granular port isolation within a single broadcast domain. When extending a PVLAN across multiple switches (S1 to S2), the secondary VLANs (Community or Isolated) must be preserved across the trunk links.

802.1Q Tagging (Option B): For traffic from a Community VLAN (RND) to reach members on a different switch, the Community VLAN must have its own 802.1Q VLAN tag (VLAN ID) associated with it. When a frame from a community port on S1 traverses the trunk to S2, it is tagged with this specific secondary VLAN ID. S2 receives the tagged frame, identifies it as belonging to the RND community, and forwards it to the appropriate community or promiscuous ports.

Why it fails without a tag: If the RND community is only defined locally on S1 without a global VLAN ID, the trunk port will not know how to distinguish that traffic from the Primary VLAN or other communities.

Incorrect Options: Option A is incorrect because the community VLAN must have a different tag than the parent (Primary) VLAN to maintain the internal PVLAN logic. Option C is incorrect because stripping tags would lead to the traffic being merged into the native VLAN or dropped. Option D is incorrect because RND is a community VLAN; changing it to an isolated VLAN would change its behavior (preventing communication between members of that same group).

This question focuses on port security and preventing " rogue switches " or multiple devices from accessing a single physical port simultaneously.

Single-Secure Supplicant Mode (Option A): This is the most restrictive 802.1X mode in Junos OS. It allows exactly one MAC address to be authenticated on the port at a time. If a device successfully authenticates, the switch will drop any traffic coming from any other MAC address on that same physical interface. If a user tries to plug in a switch, only the first device that authenticates will have access; all other devices behind that switch will be blocked.

Single Supplicant Mode (Option C): This mode allows the first authenticated user to " open " the port for all other users. This would actually allow a rogue switch to function once the first device is authorized.

Multiple Supplicant Mode (Option B): This allows multiple devices to connect, provided each one authenticates individually. While secure, it does not prevent a user from connecting multiple devices to the port, which violates the requirement to allow only one.

MAC-RADIUS (Option D): This is an authentication method, not a port-access mode that limits the number of supplicants.