[Sep 18, 2025] JN0-664 Exam Brain Dumps - Study Notes and Theory
Pass Juniper JN0-664 Test Practice Test Questions Exam Dumps
NEW QUESTION # 26
Exhibit.
Referring to the exhibit; the 10.0.0.0/24 EBGP route is received on R5; however, the route is being hidden.
What are two solutions that will solve this problem? (Choose two.)
- A. On R4, add the internal IBGP interface prefixes to the BGP routing tables.
- B. On R4, create a policy to change the BGP next hop to itself and apply it to IBGP as an export policy.
- C. On R4, create a policy to change the BGP next hop to 172.16.1.1 and apply it to IBGP as an export policy.
- D. On R4, add the external EBGP interface's prefix to the IGP routing tables.
Answer: B,D
NEW QUESTION # 27
Exhibit
You want to use both links between R1 and R2 Because of the bandwidth difference between the two links, you must ensure that the links are used as much as possible.
Which action will accomplish this goal?
- A. Disable multipath.
- B. Ensure that the metric-out parameter on the Gigabit Ethernet interface is higher than the 10 Gigibit Ethernet interface.
- C. Define a policy to tag routes with the appropriate bandwidth community.
- D. Enable per-prefix load balancing.
Answer: C
Explanation:
https://www.juniper.net/documentation/us/en/software/junos/sampling-forwarding-monitoring/bgp/topics/concep
NEW QUESTION # 28
Refer to the exhibit.
Click the Exhibit button.
You are troubleshooting an issue for a customer site that uses 10.10.0.0/24 in AS 65224, but you see another AS in the AS path.
Referring to the exhibit, what is the cause of the problem?
- A. AS 65137 is advertising the 10.10.0.0/24 prefix.
- B. AS 65000 is pre-pending AS 65137 to route advertisements.
- C. The local AS is in the process of withdrawing the route from AS 65137.
- D. The local AS is receiving two equal cost routes to 10.10.0.0/24.
Answer: A
NEW QUESTION # 29
When building an interprovider VPN, you notice on the PE router that you have hidden routes which are received from your BGP peer with family inet labeled-unica3t configured.
Which parameter must you configure to solve this problem?
- A. Under the protocols ospf hierarchy, add the traffic-engineering parameter.
- B. Under the family inet labeled-unicast hierarchy, add the explicit null parameter.
- C. Under the protocols mpls hierarchy, add the traffic-engineering parameter
- D. Under the family inet labeled-unicast hierarchy, add the resolve-vpn parameter.
Answer: D
Explanation:
Explanation
The resolve-vpn parameter is a BGP option that allows a router to resolve labeled VPN-IPv4 routes using unlabeled IPv4 routes received from another BGP peer with family inet labeled-unicast configured. This option enables interprovider VPNs without requiring MPLS labels between ASBRs or using VRF tables on ASBRs. In this scenario, you need to configure the resolve-vpn parameter under [edit protocols bgp group external family inet labeled-unicast] hierarchy level on both ASBRs.
NEW QUESTION # 30
You have an L2VPN connecting two CEs across a provider network that runs OSPF. You have OSPF configured on both CEs.
Which two statements are correct in this scenario? (Choose two.)
- A. OSPF neighborship is formed between the CEs and PEs.
- B. OSPF neighborship is formed between the two CEs.
- C. The CE and PE OSPF areas can be different.
- D. The CE and PE OSPF areas must match.
Answer: B,C
Explanation:
In an L2VPN scenario, the provider network connects two customer edge (CE) devices across a Layer 2 virtual private network. Let's analyze how OSPF operates in this setup.
1. **OSPF Neighborship in L2VPN**:
- An L2VPN provides a Layer 2 connection between two sites, making it transparent to Layer 3 protocols like OSPF. This means the CEs can form OSPF adjacencies directly with each other as if they were on the same local network.
2. **OSPF Configuration on CEs and PEs**:
- **Statement A: OSPF neighborship is formed between the CEs and PEs**:
- Incorrect. In an L2VPN, the provider's network is transparent to the OSPF running on the CEs. OSPF neighborship forms directly between the CEs, not between the CEs and PEs.
- **Statement B: The CE and PE OSPF areas can be different**:
- Correct. Since OSPF adjacencies form directly between the CEs and not between CEs and PEs, the OSPF areas on the CEs and PEs can be different. The provider network acts as a transparent bridge, and OSPF doesn't see the PEs.
- **Statement C: The CE and PE OSPF areas must match**:
- Incorrect. As noted above, because the OSPF neighborship forms directly between the CEs, the OSPF areas on the CEs and PEs do not need to match.
- **Statement D: OSPF neighborship is formed between the two CEs**:
- Correct. The L2VPN makes the connection between the two CEs appear as a direct Layer 2 link, allowing them to form an OSPF adjacency directly.
**Conclusion**:
Given the above analysis, the correct statements are:
**B. The CE and PE OSPF areas can be different.**
**D. OSPF neighborship is formed between the two CEs.**
**References**:
- Juniper Networks Documentation on L2VPNs: [Configuring Layer 2
VPNs](https://www.juniper.net/documentation/en_US/junos/topics/task/configuration/layer-2-vpns-configuring.
- OSPF Configuration Guide: [Junos OS OSPF
Configuration](https://www.juniper.net/documentation/en_US/junos/topics/concept/ospf-routing-overview.html)
NEW QUESTION # 31
Exhibit
Which two statements about the configuration shown in the exhibit are correct? (Choose two.)
- A. A Layer 3 VPN is configured.
- B. This VPN connects customer sites that use different AS numbers.
- C. A Layer 2 VPN is configured.
- D. This VPN connects customer sites that use the same AS number
Answer: A,D
Explanation:
The provided configuration is for a routing instance named VPN-A on a Juniper PE (Provider Edge) router. Let's break it down:
* Instance Type: VRF
* The instance-type vrf; statement indicates that this is a Layer 3 VPN (L3VPN) using MPLS VPNs (RFC 4364 - BGP/MPLS IP VPNs).
* This confirms that Option D (A Layer 3 VPN is configured) is correct #.
* VRF Target and Interface Association
* The vrf-target target:64512:1234; defines the route target (RT) for importing and exporting VPN routes.
* The interface ge-0/0/1.0; binds this interface to the VRF.
* BGP Configuration for CE (Customer Edge) Peering
* The group CE section configures external BGP (EBGP) (type external;).
* The neighbor 10.0.0.1 is in AS 64512 (peer-as 64512;).
* The as-override; statement is used.
Evaluating the Answer Choices
# Option B: "This VPN connects customer sites that use the same AS number."
* The as-override; command allows multiple customer sites that use the same AS number (64512) to communicate over the service provider's MPLS network.
* Normally, BGP prevents routes with the same AS in the AS_PATH from being accepted. The as- override feature replaces the customer's AS number with the provider's AS, ensuring proper route advertisement.
# This statement is correct.
# Option A: "This VPN connects customer sites that use different AS numbers."
* If the customer sites had different AS numbers, there would be no need for as-override.
* The as-override feature is specifically used when all customer sites share the same AS number, ensuring that BGP routes are accepted.
# This statement is incorrect.
# Option C: "A Layer 2 VPN is configured."
* A Layer 2 VPN (L2VPN) configuration would typically use instance-type l2vpn; or EVPN/VPLS- related parameters (e.g., protocols l2vpn or protocols vpls).
* Since this configuration uses instance-type vrf; and BGP with a VRF target, it is clearly a Layer 3 VPN (L3VPN).
# This statement is incorrect.
# Option D: "A Layer 3 VPN is configured."
* The instance-type vrf; confirms this is an MPLS Layer 3 VPN (L3VPN).
* VRFs, BGP, and route targets (vrf-target) are specific to Layer 3 VPNs.
# This statement is correct.
# B. This VPN connects customer sites that use the same AS number.
# D. A Layer 3 VPN is configured.
Verification from Juniper Documentation:
* Juniper BGP/MPLS Layer 3 VPNs Guide confirms that instance-type vrf is used for L3VPNs.
* Juniper BGP Configuration Guide states that as-override is applied when customer sites use the same AS number.
* RFC 4364 (BGP/MPLS IP VPNs) explains how route targets and VRFs are used in L3VPN deployments.
NEW QUESTION # 32
Exhibit
user@Rl show configuration interpolated-profile { interpolate {
fill-level [ 50 75 drop-probability [ > }
class-of-service drop-profiles
];
20 60 ];
Which two statements are correct about the class-of-service configuration shown in the exhibit? (Choose two.)
- A. The drop probability jumps immediately from 20% to 60% when the queue level reaches 75% full.
- B. To use this drop profile, you apply it directly to an interface.
- C. To use this drop profile, you reference it in a scheduler.
- D. The drop probability gradually increases from 20% to 60% as the queue level increases from 50% full to
75% full
Answer: C,D
Explanation:
Explanation
class-of-service (CoS) is a feature that allows you to prioritize and manage network traffic based on various criteria, such as application type, user group, or packet loss priority. CoS uses different components to classify, mark, queue, schedule, shape, and drop traffic according to the configured policies.
One of the components of CoS is drop profiles, which define how packets are dropped when a queue is congested. Drop profiles use random early detection (RED) algorithm to drop packets randomly before the queue is full, which helps to avoid global synchronization and improve network performance. Drop profiles can be discrete or interpolated. A discrete drop profile maps a specific fill level of a queue to a specific drop probability. An interpolated drop profile maps a range of fill levels of a queue to a range of drop probabilities and interpolates the values in between.
In the exhibit, we can see that the class-of-service configuration shows an interpolated drop profile with two fill levels (50 and 75) and two drop probabilities (20 and 60). Based on this configuration, we can infer the following statements:
* The drop probability jumps immediately from 20% to 60% when the queue level reaches 75% full. This is not correct because the drop profile is interpolated, not discrete. This means that the drop probability gradually increases from 20% to 60% as the queue level increases from 50% full to 75% full. The drop probability for any fill level between 50% and 75% can be calculated by using linear interpolation formula.
* The drop probability gradually increases from 20% to 60% as the queue level increases from 50% full to
75% full. This is correct because the drop profile is interpolated and uses linear interpolation formula to calculate the drop probability for any fill level between 50% and 75%. For example, if the fill level is
60%, the drop probability is 28%, which is calculated by using the formula: (60 - 50) / (75 - 50) * (60 -
20) + 20 = 28.
* To use this drop profile, you reference it in a scheduler. This is correct because a scheduler is a component of CoS that determines how packets are dequeued from different queues and transmitted on an interface. A scheduler can reference a drop profile by using the random-detect statement under the
[edit class-of-service schedulers] hierarchy level. For example: scheduler test { transmit-rate percent 10; buffer-size percent 10; random-detect test-profile; }
* To use this drop profile, you apply it directly to an interface. This is not correct because a drop profile cannot be applied directly to an interface. A drop profile can only be referenced by a scheduler, which can be applied to an interface by using the scheduler-map statement under the [edit class-of-service interfaces] hierarchy level. For example: interfaces ge-0/0/0 { unit 0 { scheduler-map test-map; } }
NEW QUESTION # 33
A router running IS-IS is configured with an ISO address of 49.0001.00a0.c96b.c490.00.
Which part of this address is the system ID?
- A. c490 is the system identifier.
- B. 00a0.c96b.c490 is the system identifier.
- C. c96b.c490 is the system identifier.
- D. 0001.00a0.c96b.c490 is the system identifier.
Answer: B
Explanation:
In IS-IS (Intermediate System to Intermediate System) routing, each router is identified by a unique ISO (International Organization for Standardization) address, also known as a Network Entity Title (NET). The NET consists of three parts:
1. **Area Identifier**: Indicates the area to which the router belongs.
2. **System Identifier**: Uniquely identifies the router within the area.
3. **NSAP Selector (NSEL)**: Typically set to 00 for a router, indicating the Network Service Access Point.
The format of the ISO address is `49.XXXX.YYYY.YYYY.ZZZZ.ZZZZ.00`, where:
- `49` is the AFI (Authority and Format Identifier) indicating a private address.
- `XXXX` is the Area Identifier.
- `YYYY.YYYY.YYYY` is the System Identifier.
- `ZZZZ.ZZZZ` is the NSAP Selector.
Given the address `49.0001.00a0.c96b.c490.00`:
- **Area Identifier**: `49.0001`
- **System Identifier**: `00a0.c96b.c490`
- **NSAP Selector**: `00`
**Explanation**:
- **A. 00a0.c96b.c490 is the system identifier**:
- Correct. The System Identifier in an ISO address is a 48-bit (6-byte) field used to uniquely identify the router. In this address, `00a0.c96b.c490` is the correct 6-byte System Identifier.
- **B. 0001.00a0.c96b.c490 is the system identifier**:
- Incorrect. This includes the Area Identifier as part of the System Identifier, which is not correct.
- **C. c96b.c490 is the system identifier**:
- Incorrect. This is only part of the System Identifier. The full System Identifier must be 6 bytes long.
- **D. c490 is the system identifier**:
- Incorrect. This is an incomplete and incorrect part of the System Identifier.
**Conclusion**:
The correct part of the address that represents the System Identifier is:
**A. 00a0.c96b.c490 is the system identifier.**
**Reference**:
- Juniper Networks Documentation on IS-IS: [IS-IS Configuration](https://www.juniper.net/documentation/en_US/junos/topics/task/configuration/isis-configuring.html)
- ISO/IEC 10589, the IS-IS routing protocol standard.
NEW QUESTION # 34 
Click the Exhibit button.
You have an EVI implemented between PE-1, PE-2, and PE-3 to allow communication between CE-1 and CE-
2. CE-2 receives unicast traffic from CE-1 on both links to PE-2 and
PE-3. When CE-1 sends broadcast traffic, CE-2 receives it on only one of the multihomed links.
Referring to the exhibit, which EVPN route type enables this behavior?
- A. Type 2
- B. Type 1
- C. Type 3
- D. Type 4
Answer: C
Explanation:
In the context of Ethernet VPN (EVPN) and the behavior described in the exhibit, it's essential to understand the different EVPN route types and their specific functionalities. Here, CE-2 is receiving unicast traffic on both of its multihomed links to PE-2 and PE-3, but broadcast traffic is received only on one of these links.
**Explanation of EVPN Route Types**:
1. **Type 1 (Ethernet Auto-Discovery Routes)**:
- These routes are used for auto-discovery of Ethernet segments and for advertising VLAN membership.
- They do not directly influence the behavior described in the question.
2. **Type 2 (MAC/IP Advertisement Routes)**:
- These routes are used to advertise MAC addresses and IP-to-MAC bindings within the EVPN.
- They handle unicast traffic forwarding and are crucial for populating the MAC address tables on the PE devices.
- While important, they do not explain the selective broadcast behavior.
3. **Type 3 (Inclusive Multicast Ethernet Tag Routes)**:
- These routes are used to build multicast distribution trees for delivering broadcast, unknown unicast, and multicast (BUM) traffic.
- They ensure that BUM traffic is sent only once per Ethernet segment, preventing duplicate frames from being sent to multihomed CEs.
- This aligns with the behavior described where CE-2 receives broadcast traffic on only one link to prevent duplication.
4. **Type 4 (Ethernet Segment Routes)**:
- These routes are used to advertise the presence of an Ethernet segment and are crucial for Designated Forwarder (DF) election processes in multihoming scenarios.
- While relevant to multihoming, they are not directly responsible for the selective broadcast behavior.
**Conclusion**:
The behavior described, where CE-2 receives broadcast traffic on only one of its multihomed links, is controlled by Type 3 routes. These routes are specifically designed to handle inclusive multicast and broadcast traffic efficiently in EVPN environments, ensuring that such traffic is not duplicated across multiple links to the same CE.
**References**:
- Juniper Networks EVPN Documentation: [EVPN Overview](https://www.juniper.net/documentation/en_US
/junos/topics/concept/evpn-overview.html)
- RFC 7432, BGP MPLS-Based Ethernet VPN: [RFC 7432](https://tools.ietf.org/html/rfc7432) provides detailed descriptions of EVPN route types and their functions.
- Junos OS EVPN Configuration Guide: [Junos OS EVPN Configuration Guide](https://www.juniper.net
/documentation/en_US/junos/topics/topic-map/evpn.html)
NEW QUESTION # 35
Exhibit
You are asked to exchange routes between R1 and R4 as shown in the exhibit. These two routers use the same AS number Which two steps will accomplish this task? (Choose two.)
- A. Configure the BGP group with the advertise-peer-as parameter on R2 and R3.
- B. Configure the BGP group with the as-override parameter on R2 and R3
- C. Configure the BGP group with the advertise-peer-as parameter on R1 and R4.
- D. Configure the BGP group with the as-override parameter on R1 and R4
Answer: B,C
Explanation:
Explanation
The advertise-peer-as parameter allows a router to advertise its peer's AS number as part of the AS path attribute when sending BGP updates to other peers. This parameter is useful when two routers in the same AS need to exchange routes through another AS, such as in the case of R1 and R4. By configuring this parameter on R1 and R4, they can advertise each other's AS number to R2 and R3, respectively.
The as-override parameter allows a router to replace the AS number of its peer with its own AS number when receiving BGP updates from that peer. This parameter is useful when two routers in different ASes need to exchange routes through another AS that has the same AS number as one of them, such as in the case of R2 and R3. By configuring this parameter on R2 and R3, they can override the AS number of R1 and R4 with their own AS number when sending BGP updates to each other.
NEW QUESTION # 36
Exhibit
Which two statements about the configuration shown in the exhibit are correct? (Choose two.)
- A. This VPN connects customer sites that use the same AS number
- B. A Layer 3 VPN is configured.
- C. This VPN connects customer sites that use different AS numbers.
- D. A Layer 2 VPN is configured.
Answer: B,C
Explanation:
Explanation
The configuration shown in the exhibit is for a Layer 3 VPN that connects customer sites that use different AS numbers. A Layer 3 VPN is a type of VPN that uses MPLS labels to forward packets across a provider network and BGP to exchange routing information between PE routers and CE routers. A Layer 3 VPN allows customers to use different routing protocols and AS numbers at their sites, as long as they can peer with BGP at the PE-CE interface. In this example, CE-1 is using AS 65530 and CE-2 is using AS 65531, but they can still communicate through the VPN because they have BGP sessions with PE-1 and PE-2, respectively.
NEW QUESTION # 37 
Click the Exhibit button.
Referring to the exhibit, which two statements are true? (Choose two.)
- A. This route is learned from two different AS numbers.
- B. This route is learned from the same AS number.
- C. The multihop configuration is used for load balancing.
- D. The multipath configuration is used for load balancing.
Answer: B,D
Explanation:
In the exhibit, the output of the `show route protocol bgp` command is shown for the prefix `172.16.20.4/30`.
Let's analyze the provided BGP routing table to determine which statements are correct.
1. **AS Path Analysis**:
- The AS path for the route `172.16.20.4/30` is shown as `2 I`.
- This indicates that the route was learned from AS 2 and it is an internal (iBGP) route within the same AS.
2. **Multiple Paths**:
- The route has two next-hop IP addresses: `10.0.18.2` via interface `ge-1/0/4.0` and `10.0.19.2` via interface
`ge-1/0/5.0`.
- This indicates that BGP multipath is configured, which allows multiple equal-cost paths to be used for load balancing.
- BGP multipath must be explicitly configured to use multiple paths for the same prefix.
3. **Multihop vs. Multipath**:
- **Multihop Configuration**: This is typically used for establishing BGP sessions with peers that are not directly connected. It is not related to load balancing.
- **Multipath Configuration**: This is used to enable load balancing across multiple paths for the same prefix, which is the case here.
**Conclusion**:
Given the above analysis:
- **C. This route is learned from the same AS number**: Correct. The AS path `2 I` indicates the route was learned from the same AS number (AS 2).
- **D. The multipath configuration is used for load balancing**: Correct. The presence of multiple next-hops indicates that BGP multipath is configured for load balancing.
Thus, the correct answers are:
**C. This route is learned from the same AS number.**
**D. The multipath configuration is used for load balancing.**
**References**:
- Junos OS BGP Multipath Documentation: [Junos OS BGP
Multipath](https://www.juniper.net/documentation/en_US/junos/topics/topic-map/bgp-multipath.html)
- Junos OS BGP Configuration Guide: [Junos OS BGP
Configuration](https://www.juniper.net/documentation/en_US/junos/topics/concept/bgp-routing-overview.html)
NEW QUESTION # 38
Exhibit
R1 and R8 are not receiving each other's routes
Referring to the exhibit, what are three configuration commands that would solve this problem? (Choose three.)
- A. Configure as-override on advertisement from AS 64500 toward AS 64512.
- B. Configure loops on routers in AS 65412 and advertise-peer-as on routers in AS 64498.
- C. Configure remove-private on advertisements from AS 64500 toward AS 64499
- D. Configure loops and advertise-peer-as on routers in AS 64497 and AS 64450.
- E. Configure remove-private on advertisements from AS 64497 toward AS 64498
Answer: B,C,E
Explanation:
The problem in this scenario is that R1 and R8 are not receiving each other's routes because of private AS numbers in the AS path. Private AS numbers are not globally unique and are not advertised to external BGP peers. To solve this problem, you need to do the following:
* Configure loops on routers in AS 65412 and advertise-peer-as on routers in AS 64498. This allows R5 and R6 to advertise their own AS number (65412) instead of their peer's AS number (64498) when sending updates to R7 and R8. This prevents a loop detection issue that would cause R7 and R8 to reject the routes from R5 and R62.
* Configure remove-private on advertisements from AS 64497 toward AS 64498 and from AS 64500
* toward AS 64499. This removes any private AS numbers from the AS path before sending updates to external BGP peers. This allows R2 and R3 to receive the routes from R1 and R4, respectively3.
NEW QUESTION # 39
You are a network architect for a service provider and want to offer Layer 2 services to your customers You want to use EVPN for Layer 2 services in your existing MPLS network.
Which two statements are correct in this scenario? (Choose two.)
- A. Segment routing must be configured on all PE routers.
- B. VXLAN must be configured on all PE routers.
- C. EVPN uses Type 3 routes to join a multicast tree to flood traffic.
- D. EVPN uses Type 2 routes to advertise MAC address and IP address pairs learned using ARP snooping
Answer: C,D
Explanation:
EVPN is a technology that connects L2 network segments separated by an L3 network using a virtual Layer 2 network overlay over the Layer 3 network. EVPN uses BGP as its control protocol to exchange different types of routes for different purposes. Type 2 routes are used to advertise MAC address and IP address pairs learned using ARP snooping from the local CE devices. Type 3 routes are used to join a multicast tree to flood traffic such as broadcast, unknown unicast, and multicast (BUM) traffic.
NEW QUESTION # 40
Referring to the exhibit, the PE-to-CE protocol being used is OSPF for the L3VPN. Also, there is an OSPF neighborship between CE-1 and CE-2.
Which statement is correct in this situation?
- A. Hosts at Site-1 will reach hosts at Site-2 through the CE-1 and CE-2 link by default.
- B. You must set a high metric on the CE-1 to PE-1 link for hosts at Site-1 to use the CE-1 to CE-2 link to reach hosts at Site-2.
- C. Hosts at Site-1 will reach hosts at Site-2 through the L3VPN by default.
- D. You must set a high metric on the CE-1 to CE-2 link for hosts at Site-1 to use the L3VPN to reach hosts at Site-2.
Answer: A
NEW QUESTION # 41
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