Juniper JN0-649 Exam Dumps & Practice Test Questions

Question 1:

While investigating a BGP session failure, the system log reveals specific error messages related to session establishment attempts with peers at 192.168.1.4 and 192.168.1.5. 

Based on the output, which two conclusions can be made? (Choose two.)

A. Packet fragmentation is causing the BGP session to fail.
B. The peer at 192.168.1.5 has an incorrect MD5 authentication configuration.
C. The interface ge-0/0/1 is administratively down.
D. The peer at 192.168.1.4 is configured with the wrong autonomous system number.

Correct Answers: B, D

Explanation:

In this scenario, we analyze logs related to BGP session troubleshooting. These logs provide two key clues: one involving an MD5 digest error from a peer at IP address 192.168.1.5, and another referencing a BGP notification about an autonomous system number mismatch from 192.168.1.4.

Let’s begin with the peer at 192.168.1.5. The log message indicates:
tcp_auth_ok: Packet from 192.168.1.5:64047 missing MD5 digest
This error means the BGP packet lacked the expected MD5 signature. In BGP, if MD5 authentication is enabled and the received packet does not include a correct or any digest, the connection is immediately rejected. This suggests the remote side either isn’t configured for MD5 at all or is using an incorrect key, confirming B is correct.

Next, regarding 192.168.1.4, we see:
NOTIFICATION sent to 192.168.1.4 ... subcode 2 (bad peer AS number), Reason: peer 192.168.1.4 (Internal AS 65000) claims 65100, 65000 configured
This message clearly shows an AS number mismatch between the local configuration and the BGP OPEN message received from the peer. The local device expects AS 65000, but the peer is using 65100. This is a typical configuration error, confirming D as the second correct choice.

Now, analyzing the incorrect options:

A. There's no indication in the logs about MTU issues or IP fragmentation. Fragmentation errors would typically include warnings like “fragmentation needed” or ICMP unreachable errors, none of which are present. So this is incorrect.

C. While the log references interface ge-0/0/1.0, there are no indications that the interface is down. You would expect link-down messages or carrier loss logs if the interface were disabled. Hence, this is also incorrect.

To conclude, the evidence supports two specific problems:

• The peer at 192.168.1.5 is not properly using MD5 authentication.

• The peer at 192.168.1.4 is using the wrong AS number in its configuration.

Thus, the correct answers are B and D.

Question 2:

In a multicast environment using anycast RP, a source is actively sending traffic to multicast group 239.1.1.1. Router R3 is receiving PIM register messages, while R2 does not have source information. 

What are two ways to ensure that R2 also becomes aware of the multicast source? (Choose two.)

A. Set up a PIM RP set on R1 to allow forwarding of register messages to both R2 and R3.
B. Establish MSDP peering between R2 and R3.
C. Configure a shared RP set on R2 and R3 in PIM to propagate register messages.
D. Enable MSDP between R1 and R2.

Correct Answers: B, D

Explanation:

This scenario highlights the behavior of anycast Rendezvous Points (RPs) in a multicast network and how they share source information. In anycast RP configurations, multiple routers are configured with the same IP address as the RP. This ensures high availability and redundancy. However, for this system to function correctly, the RPs must exchange information about multicast sources.

In the described case, router R3 is actively receiving PIM register messages from the multicast source, while R2—despite being part of the anycast RP configuration—lacks source information. This means multicast receivers depending on R2 will not receive the stream unless the missing data is shared with it.

To resolve this, the Multicast Source Discovery Protocol (MSDP) is used. MSDP enables the exchange of source information (active source announcements) between RPs in different multicast domains or across anycast RP configurations.

Option B is correct because setting up MSDP peering between R2 and R3 allows R3 to share source information it receives via PIM registers with R2. This ensures both RPs are synchronized in terms of source knowledge.

Option D is also correct if R1 is part of the multicast routing infrastructure and receives PIM register messages. Establishing MSDP between R1 and R2 would allow source information known to R1 to be propagated to R2, solving the same problem from a different peering angle.

Now, reviewing the incorrect choices:

Option A refers to configuring an “RP set” in PIM. PIM itself does not provide any mechanism for forwarding register messages to multiple RPs. Registers are always unicast to the configured RP for the group, and there is no built-in redundancy at the PIM level. So this option is invalid.

Option C is incorrect for a similar reason. PIM does not support propagating register messages among RPs. The function of disseminating source info among RPs is the specific purpose of MSDP, not PIM.

In conclusion, the only effective way to synchronize multicast source information among RPs in an anycast RP setup is by implementing MSDP peering between the appropriate routers. Therefore, the correct answers are B and D.

Question 3:

You need to implement authentication at the network interface level to ensure that only approved corporate devices are allowed to connect. The devices are identified based on their MAC addresses, and authentication must be handled by a centralized server for better scalability. 

Which method should you choose?

A. MAC RADIUS
B. Captive Portal
C. 802.1X with single-secure supplicant mode
D. 802.1X with multiple supplicant mode

Correct answer: A

Explanation:

The scenario describes the need for device-level authentication, specifically using MAC addresses, and a centralized approach that scales well. These conditions align perfectly with MAC RADIUS, also known as MAC Authentication Bypass (MAB). This method is commonly used for authenticating devices like printers, IP phones, and other endpoints that lack support for 802.1X or don't run a supplicant.

With MAC RADIUS, the network switch forwards the MAC address of the connecting device to a central RADIUS server, which verifies whether the MAC address is on an approved list. This eliminates the need for user interaction and allows headless devices to authenticate transparently. It also enables centralized control and logging, making it easier to manage in larger enterprise environments.

Let’s analyze why the other options fall short:

• B. Captive Portal:
  This is designed for user-based web authentication. It redirects clients to a login page upon connecting to the network. Since it requires user interaction and is not suitable for device-level or MAC-based access control, it’s not appropriate here.

• C. 802.1X with Single-Secure Supplicant Mode:
  This mode provides authentication for one user per port using a supplicant that runs on the device. While it works for user-level credentials and secure access, it does not support MAC-based authentication. Devices that can’t run 802.1X clients (like many IoT or legacy hardware) would be excluded.

• D. 802.1X with Multiple Supplicant Mode:
  This variation allows multiple authenticated clients on the same port, which is helpful in shared environments (e.g., VoIP phones with daisy-chained PCs). But again, it depends on each device running a supplicant and doesn’t offer MAC-based authentication.

In summary, MAC RADIUS provides a seamless, centralized solution for authenticating corporate devices via their MAC addresses at the port level. It is scalable, non-intrusive, and widely used in enterprise networks, especially when dealing with non-user-facing hardware.

Question 4:

Refer to the exhibit. A RIP-learned route (192.168.1.0/24) is being redistributed into the OSPF domain from a router located in a Not-So-Stubby Area (NSSA). What OSPF LSA type is used to initially advertise this route?

A. Type 5
B. Type 4
C. Type 3
D. Type 7

Correct answer: D

Explanation:

This question focuses on how external routes—such as those learned via RIP—are introduced into an OSPF domain when the redistribution happens inside an NSSA (Not-So-Stubby Area).

Let’s begin by understanding the process. When an external route (like 192.168.1.0/24) is redistributed into OSPF from a router inside an NSSA, the standard Type 5 LSA (used for external routes in regular areas) cannot be used because Type 5 LSAs are not allowed in NSSA areas. Instead, OSPF uses Type 7 LSAs for this purpose.

In this case, the router performing redistribution (R1) generates a Type 7 LSA to describe the external RIP route. This LSA is flooded within the NSSA, making it visible to other routers in that area.

Then, when the Type 7 LSA reaches the ABR (Area Border Router)—let’s say R2—it converts the Type 7 LSA into a Type 5 LSA and injects it into the backbone area (Area 0). From there, it is distributed throughout the rest of the OSPF domain, eventually reaching R5.

However, the question specifically asks how the route is advertised, not how it travels beyond the NSSA. Since the initial LSA type used in the NSSA is a Type 7, that is the correct answer.

Let’s eliminate the incorrect options:

• A. Type 5:
  Used for external routes but not allowed in NSSA areas. This LSA only appears after translation by the ABR.

• B. Type 4:
  Used to advertise the location of the ASBR (the router doing the redistribution), not the route itself. It assists in finding the ASBR but doesn’t carry route data.

• C. Type 3:
  These are summary LSAs used to advertise inter-area routes, such as those learned in other OSPF areas. They are not used for external route advertisement.

Therefore, since the RIP route enters the OSPF domain from an NSSA, it is originally carried via a Type 7 LSA, making D the correct answer.

Question 5:

When configuring MVRP (Multiple VLAN Registration Protocol), which statement accurately describes the behavior of the 'forbidden' mode on an interface?

A. The forbidden mode does not register or declare VLANs
B. MVRP, once activated, applies to all interfaces by default
C. Timers in MVRP control how link-state changes are shared
D. MVRP operates in tandem with RSTP and VSTP

Correct Answer: A

Explanation:

The correct choice is A, as it accurately reflects the function of the ‘forbidden’ mode in MVRP (Multiple VLAN Registration Protocol). MVRP is an IEEE standard protocol used to dynamically advertise, register, and prune VLAN information between switches on a network. It eliminates the need for manual VLAN configuration on each switch port, simplifying VLAN propagation across large Layer 2 domains.

MVRP operates through different interface modes, each dictating how VLAN information is managed:

• Normal Mode: The default setting where interfaces both declare and register VLANs.

• Forbidden Mode: This mode prohibits the interface from participating in MVRP. That means it neither registers VLANs from other devices nor declares VLANs to others. It enforces strict control to prevent unintended VLAN propagation.

• Fixed Mode: VLANs are statically defined; MVRP will not modify them.

• Dynamic Mode: VLANs are dynamically created or removed based on MVRP advertisements.

In forbidden mode, MVRP ensures no VLANs are learned or advertised through that specific interface. This is particularly useful in securing VLAN boundaries or where dynamic VLAN changes are undesirable.

Let’s examine why the other options are incorrect:

• B. MVRP does not globally apply to all interfaces by default. It operates per interface, meaning administrators must enable or configure it individually on each interface where dynamic VLAN management is needed.

• C. While MVRP does use timers (join timer, leave timer, leave-all timer), these timers are responsible for VLAN advertisement and registration intervals, not link-state changes. Link-state propagation is handled by protocols like STP (Spanning Tree Protocol), not MVRP.

• D. MVRP may coexist with protocols like RSTP or VSTP, but it does not actively integrate with them. Its function is focused purely on VLAN registration, independent of the spanning tree behavior.

In summary, MVRP’s forbidden mode provides a mechanism to strictly control VLAN learning and advertisement on a port. This helps maintain network security and stability in environments where dynamic VLAN changes should not occur. Hence, the correct answer is A.

Question 6:

Which IP address range is specifically designated for source-specific multicast (SSM)?

A. 239.0.0.0/8
B. 233.0.0.0/8
C. 232.0.0.0/8
D. 224.2.0.0/16

Correct Answer: C

Explanation:

The correct answer is C, as 232.0.0.0/8 is the address range reserved exclusively for Source-Specific Multicast (SSM). SSM is a multicast delivery model in which receivers specify both the IP address of the source and the IP multicast group address from which they want to receive traffic. This offers enhanced security, performance, and filtering compared to Any-Source Multicast (ASM).

SSM is defined in RFC 4607, and it introduces a more efficient method of multicast distribution where hosts request traffic in the form of (S, G) — that is, from a specific source (S) to a specific group (G). This removes the need for complex source discovery protocols, simplifies routing decisions, and ensures that receivers only get data they explicitly request.

The 232.0.0.0/8 range is used with protocols like IGMPv3 (Internet Group Management Protocol version 3) and PIM-SSM (Protocol Independent Multicast - Source Specific Multicast) to manage receiver requests and traffic forwarding.

Let’s review why the other address ranges are incorrect:

• A. 239.0.0.0/8: This is the administratively scoped multicast range, similar in concept to private IP ranges (e.g., 10.0.0.0/8 in unicast). It is used for multicast within an organization and is not used for SSM.

• B. 233.0.0.0/8: This block was allocated for GLOP addressing, a method for assigning multicast addresses based on an Autonomous System Number (ASN). It’s a legacy system and unrelated to the SSM model.

• D. 224.2.0.0/16: This range is allocated for global-scope multicast applications, including the Session Announcement Protocol (SAP) and other MBone (Multicast Backbone) services. It is used in traditional ASM models and not in SSM.

Using SSM provides several benefits:

• Improved security by restricting data flow to a known source.

• Better network performance and resource usage.

• No need for complex shared tree or RP (Rendezvous Point) configurations.

In conclusion, only 232.0.0.0/8 is officially assigned for SSM and is supported by modern multicast deployments to optimize and secure multicast traffic. Therefore, the correct choice is C.

Question 7:

Which three configuration settings must be identical on all switches to ensure they belong to the same MSTP region? (Select three.)

A. VLAN to instance mapping
B. Revision level
C. Configuration name
D. Bridge priority
E. Region name

Correct answers: A, B, C

Explanation:

This question examines the key configuration parameters necessary for switches to be part of the same Multiple Spanning Tree Protocol (MSTP) region. MSTP is an advanced version of Spanning Tree Protocol designed to improve network scalability by enabling multiple VLANs to be grouped into fewer spanning tree instances, reducing overhead and optimizing network traffic.

For MSTP to correctly form a single logical region that spans multiple switches, three core configuration elements must be consistent across all switches in that region: the configuration name, the revision level, and the VLAN-to-instance mapping.

• Configuration Name (C): This is a case-sensitive string that uniquely identifies the MST region. It acts as a regional identifier, so all switches within the same MST region must have exactly the same configuration name. If this does not match, switches will treat themselves as belonging to separate MST regions, causing disjointed spanning trees.

• Revision Level (B): This numeric value indicates the version of the MST configuration. It allows switches to detect configuration changes across the region. All switches must have the same revision level for them to consider their MST configuration aligned. A mismatch here means the switches will assume different versions of the MST configuration, splitting the region.

• VLAN to Instance Mapping (A): MSTP lets you associate multiple VLANs with particular spanning tree instances (STIs). This mapping determines which VLANs participate in which instance, affecting how traffic is routed and blocked within the MST region. For consistency and correct operation, every switch must have the exact same VLAN-to-instance mapping.

Why the other options are not correct:

• Bridge Priority (D): This value influences which switch becomes the root bridge of the spanning tree but does not affect MST region membership. Different switches can have different priorities within the same region.

• Region Name (E): This term is often confused with the configuration name, but MSTP relies solely on the configuration name parameter. There is no separate "region name" field in MSTP configuration.

In summary, ensuring the configuration name, revision level, and VLAN to instance mapping are uniform across switches is essential for them to operate cohesively within the same MST region. Any discrepancy will cause MSTP to segment the network into different regions, potentially resulting in suboptimal paths, network loops, or broadcast storms.

Question 8:

Which two statements correctly describe the EVPN-VXLAN deployment on Juniper QFX Series switches? (Choose two.)

A. Type 1 route advertisements always have the single-active flag set to 1.
B. Junos OS supports underlay replication for BUM traffic forwarding.
C. Junos OS supports ingress replication for BUM traffic forwarding.
D. Type 1 route advertisements always have the single-active flag set to 0.

Correct answers: B, C

Explanation:

This question targets your knowledge about EVPN-VXLAN implementation specifics on Juniper QFX Series devices, focusing on BUM (Broadcast, Unknown Unicast, Multicast) traffic handling and the behavior of Type 1 EVPN routes.

EVPN-VXLAN is a popular technology used to extend Layer 2 networks over Layer 3 infrastructures, enabling flexible and scalable data center fabrics. A key challenge in EVPN-VXLAN networks is efficiently replicating BUM traffic, which must be flooded to all relevant endpoints because the destination is unknown or multicast-based.

Junos OS supports two main methods to handle this BUM traffic replication:

• Underlay Replication (Multicast-based): This approach uses IP multicast groups in the underlay network to distribute BUM traffic efficiently. When multicast is enabled and the underlying network infrastructure supports it, this method scales well for large environments because traffic is replicated only once per multicast group, reducing bandwidth consumption.

• Ingress Replication: In this model, the originating VTEP (VXLAN Tunnel Endpoint) sends a separate copy of BUM traffic to every other VTEP in the VXLAN segment. This approach is simpler to deploy because it avoids multicast dependencies but may not scale as well in large networks due to increased bandwidth usage.

Both methods (options B and C) are supported on Juniper QFX Series devices running Junos OS, offering flexibility depending on network design and capabilities.

Regarding Type 1 route advertisements, also known as Ethernet Auto-Discovery (EAD) routes, these signal the presence of Ethernet segments and their redundancy status. The single-active flag in these advertisements indicates if the redundancy model is:

• Single-active mode (flag = 1): Only one link is active at a time (e.g., LACP fallback mode).

• Active-active mode (flag = 0): Multiple links are active simultaneously.

Because the single-active flag varies according to deployment requirements, it is inaccurate to say it is always set to 0 or 1, making options A and D incorrect.

In summary, Junos OS on QFX switches supports both underlay multicast and ingress replication for BUM traffic, providing deployment flexibility. The single-active flag in Type 1 routes depends on redundancy mode rather than being fixed.

Question 9:

In an enterprise network using BGP VPNs for multitenancy, some peer devices do not support VPN NLRI. 

To prevent sending VPN routes to these incompatible peers, which two configuration steps should be implemented? (Select two.)

A. Apply an import policy on the remote peer to reject these routes when received.
B. Use an export policy on the local BGP peer to block VPN routes being sent.
C. Implement a route reflector for VPN NLRI.
D. Enable the apply-vpn-export feature on the local BGP peer.

Correct answers: B, D

Explanation:

In a BGP/MPLS VPN environment, VPN routes are advertised using VPN NLRI, which encapsulates VPN-specific reachability information. When peering with devices that do not understand VPN NLRI, it is crucial to ensure these routes are not sent to them, to avoid session failures or unpredictable network behavior.

Why Export Policies on the Local Peer (Option B) Are Essential:
An export policy applied on the local BGP peer controls which routes are advertised to neighbors. This is the most effective way to prevent sending VPN routes to peers that do not support VPN NLRI because it stops the advertisement at the source. Filtering routes here is proactive, ensuring that the incompatible peer never receives unsupported NLRI types. This approach conserves network resources and prevents potential protocol incompatibility issues.

Role of the apply-vpn-export Feature (Option D):
In Junos OS, the apply-vpn-export option is designed to ensure that VPN routes—residing inside VRF routing instances—can be filtered by export policies when leaked into global routing tables or sent to BGP peers. Without this feature, VPN routes might bypass export policies, unintentionally being advertised to peers lacking VPN support. Enabling apply-vpn-export enforces policy application on VPN routes, enabling precise control over route distribution.

Why Import Policies on Remote Peers (Option A) Are Not Ideal:
Although import policies on remote peers can reject unwanted routes, relying on remote peers to filter incompatible VPN routes is less reliable and can lead to session resets or dropped connections if unsupported NLRI is received. Preventing transmission at the source is a more robust strategy.

Why Route Reflectors (Option C) Do Not Solve This:
Route reflectors serve to optimize route distribution within internal BGP domains but do not inherently control the advertisement of VPN routes or filter VPN NLRIs for incompatible peers. Additional policy configurations are necessary if route reflectors are involved, but they do not replace the need for export policies and apply-vpn-export.

The best practice to avoid sending VPN NLRI routes to peers that don't support them involves applying an export policy on the local BGP peer to block VPN routes and enabling the apply-vpn-export feature to ensure the policy also applies to VPN routes. This dual approach guarantees clean and compatible route advertisements, maintaining stable BGP sessions and proper multitenant VPN functionality.

Question 10:

You want to configure an OSPF area that contains only intra-area route information, specifically only Type 1 and Type 2 LSAs, with no inter-area or external routes. 

Which type of OSPF area should you configure to meet this requirement?

A. Totally non-to-stubby area
B. Totally stubby area
C. Stub area
D. Not-so-stubby area (NSSA)

Correct answer: B

Explanation:

OSPF (Open Shortest Path First) areas handle different types of LSAs (Link-State Advertisements) to manage routing information distribution efficiently. LSAs provide routers with the topology and reachability information needed to build routing tables.

Types of LSAs Overview:

• Type 1 (Router LSAs): Generated by every router to describe its connected interfaces.

• Type 2 (Network LSAs): Generated by designated routers for multi-access networks.

• Type 3 (Summary LSAs): Generated by Area Border Routers (ABRs) to summarize routes between areas.

• Type 5 (External LSAs): Represent routes redistributed into OSPF from external sources.

• Type 7 (NSSA LSAs): Used in NSSAs, similar to Type 5 but within a Not-So-Stubby Area.

Requirement Recap:
You need an OSPF area restricted to only Type 1 and Type 2 LSAs, meaning the area should not receive any Type 3 (inter-area) or Type 5/7 (external) LSAs.

Analyzing Area Types:

• Stub Area: Blocks Type 5 LSAs but still allows Type 3 LSAs, meaning inter-area routes are allowed. This does not satisfy the requirement to block inter-area routes.

• Not-So-Stubby Area (NSSA): Allows Type 3, Type 7 (which can be converted to Type 5), and external routes. So, it does not restrict LSAs as strictly as needed.

• Totally Stubby Area: Blocks both Type 3 and Type 5 LSAs. Only Type 1 and Type 2 LSAs are present inside this area. ABRs inject a default route (0.0.0.0) to represent external and inter-area routes, simplifying the routing table inside the area and meeting the requirement perfectly.

• Totally Non-to-Stubby Area: This term is not standard in OSPF terminology and is likely a confusion or misnomer.

Why Totally Stubby Area is Correct:
A Totally Stubby Area is a special OSPF area that provides the strictest limitation on LSA types: only Type 1 and 2 LSAs are allowed, blocking all summary (Type 3) and external (Type 5) LSAs. It uses a default route injected by the ABR to handle routing outside the area. This ensures minimal routing information is processed inside the area, which can improve efficiency and security.

When you need an OSPF area that exclusively carries intra-area LSAs (Type 1 and Type 2), with no inter-area or external routes, a Totally Stubby Area is the correct configuration choice. It provides simplicity, reduces routing overhead, and aligns perfectly with the stated requirement.