[2025年更新]合格できるJuniper JN0-664試験最新99問題
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質問 # 41
Exhibit
CE-1 must advertise ten subnets to PE-1 using BGP Once CE-1 starts advertising the subnets to PE-1, the BGP peering state changes to Active.
Referring to the CLI output shown in the exhibit, which statement is correct?
- A. CE-1 is advertising its entire routing table.
- B. CE-1 is configured with an incorrect peer AS
- C. The prefix limit has been reached on PE-1
- D. CE-1 is unreachable
正解：B
解説：
Explanation
The problem in this scenario is that CE-1 is configured with an incorrect peer AS number for its BGP session with PE-1. The CLI output shows that CE-1 is using AS 65531 as its local AS number and AS 65530 as its peer AS number. However, PE-1 is using AS 65530 as its local AS number and AS 65531 as its peer AS number. This causes a mismatch in the BGP OPEN messages and prevents the BGP session from being established. To solve this problem, CE-1 should configure its peer AS number as 65530 under [edit protocols bgp group external] hierarchy level.
質問 # 42
Exhibit
You want Site 1 to access three VLANs that are located in Site 2 and Site 3 The customer-facing interface on the PE-1 router is configured for Ethernet-VLAN encapsulation.
What is the minimum number of L2VPN routing instances to be configured to accomplish this task?
- A. 0
- B. 1
- C. 2
- D. 3
正解：D
解説：
To allow Site 1 to access three VLANs that are located in Site 2 and Site 3, you need to configure three L2VPN routing instances on PE-1, one for each VLAN. Each L2VPN routing instance will have a different VLAN ID and a different VNI for VXLAN encapsulation. Each L2VPN routing instance will also have a different vrf-target export value to identify which VPN routes belong to which VLAN. This way, PE-1 can forward traffic from Site 1 to Site 2 and Site 3 based on the VLAN tags and VNIs.
質問 # 43
Exhibit
CE-1 must advertise ten subnets to PE-1 using BGP Once CE-1 starts advertising the subnets to PE-1, the BGP peering state changes to Active.
Referring to the CLI output shown in the exhibit, which statement is correct?
- A. CE-1 is advertising its entire routing table.
- B. CE-1 is configured with an incorrect peer AS
- C. The prefix limit has been reached on PE-1
- D. CE-1 is unreachable
正解：B
解説：
The problem in this scenario is that CE-1 is configured with an incorrect peer AS number for its BGP session with PE-1. The CLI output shows that CE-1 is using AS 65531 as its local AS number and AS 65530 as its peer AS number. However, PE-1 is using AS 65530 as its local AS number and AS 65531 as its peer AS number. This causes a mismatch in the BGP OPEN messages and prevents the BGP session from being established. To solve this problem, CE-1 should configure its peer AS number as 65530 under [edit protocols bgp group external] hierarchy level.
質問 # 44
In IS-IS, which two statements are correct about the designated intermediate system (DIS) on a multi-access network segment? (Choose two)
- A. A router with a priority of 1 wins the DIS election over a router with a priority of 10.
- B. A router with a priority of 10 wins the DIS election over a router with a priority of 1.
- C. On the multi-access network, each router forms an adjacency to every other router on the segment
- D. On the multi-access network, each router only forms an adjacency to the DIS.
正解：B、C
解説：
Option A (Correct):
In IS-IS, the Designated Intermediate System (DIS) is elected based on the highest configured priority (as defined in Junos OS).
If priorities are equal, the router with the highest MAC address becomes the DIS.
A priority value of 10 will always override a lower priority (e.g., 1).
Reference:
Option C (Correct):
On a multi-access network (e.g., Ethernet), all IS-IS routers form adjacencies with every other router on the segment.
Unlike OSPF, IS-IS does not restrict adjacencies to only the DIS.
The DIS is responsible for creating a pseudonode LSP to represent the broadcast network, but full mesh adjacencies are maintained.
Why Other Options Are Incorrect:
Option B: Incorrect. Higher priority always wins the DIS election. A priority of 1 cannot override a priority of 10.
Option D: Incorrect. IS-IS routers form adjacencies with all neighbors, not just the DIS.
Key Takeaways:
DIS Election: Prioritizes highest numerical value (e.g., 10 > 1).
Adjacency Behavior: Full mesh adjacencies are maintained, unlike OSPF.
DIS Role: Primarily for generating pseudonode LSPs and optimizing flooding, not adjacency restriction.
For further details, refer to Juniper's official IS-IS documentation:
Juniper IS-IS Configuration Guide.
https://www.juniper.net/documentation/us/en/software/junos/is-is/topics/concept/routing-protocol-is-is-security-designated-router-understanding.html
質問 # 45
Exhibit
You have MAC addresses moving in your EVPN environment
Referring to the exhibit, which two statements are correct about the sequence number? (Choose two)
- A. It helps the local PE to identify the latest advertisement.
- B. It identifies MAC addresses that should be discarded.
- C. It resolves conflicting MAC address ownership claims.
- D. It is advertised using a Type 2 message
正解：A、D
解説：
In an EVPN (Ethernet Virtual Private Network) environment, MAC address mobility is a critical feature that allows devices to move across different locations while ensuring the network consistently tracks their MAC addresses. Let's break down the components in the exhibit and analyze the correct statements.
Understanding MAC Mobility and Sequence Numbers in EVPN
In EVPN, MAC mobility is managed through sequence numbers that are included in Type 2 MAC/IP advertisements.
The sequence number tracks MAC movement events and is used to determine the most recent update when a MAC address appears on different PEs (Provider Edge devices).
When a MAC address moves between locations, the EVPN PEs increment the sequence number and advertise it to resolve conflicts and determine which PE has the most up-to-date information.
Now, Let's Review the Options:
✅ C. It helps the local PE to identify the latest advertisement.
Correct:
The sequence number plays a key role in resolving MAC address conflicts. If multiple PEs advertise the same MAC address, the PE compares the sequence numbers to determine which update is the latest.
A higher sequence number indicates a more recent MAC update.
✅ D. It is advertised using a Type 2 message.
Correct:
EVPN MAC/IP advertisements use BGP EVPN Type 2 messages to carry MAC addresses, IP addresses (optional), and their associated sequence numbers.
Type 2 advertisements are used to track MAC mobility and IP reachability information in the EVPN.
Why the Other Options Are Incorrect:
❌ A. It identifies MAC addresses that should be discarded.
Incorrect:
The sequence number doesn't identify MAC addresses that need to be discarded.
Instead, it resolves conflicts by determining the most recent MAC address advertisement based on the highest sequence number.
❌ B. It resolves conflicting MAC address ownership claims.
Partially true, but misleading:
While it's true that sequence numbers are used in conflict resolution, the sequence number itself doesn't directly resolve ownership claims. It only helps determine which advertisement is more recent. The actual conflict resolution happens through the comparison of the advertisements and sequence numbers.
Final answer:
✅ C. It helps the local PE to identify the latest advertisement.
✅ D. It is advertised using a Type 2 message.
Reference from Juniper Documentation:
Juniper EVPN Configuration Guide:
"In EVPN MAC/IP advertisements, sequence numbers track the mobility of MAC addresses and are used to resolve conflicts when the same MAC address is advertised by multiple PEs. The PE with the higher sequence number has the most recent information." Juniper BGP EVPN Mobility Documentation
質問 # 46
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. Add the external interface prefix to the IGP 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. Add the internal interface prefix to the BGP routing tables.
- D. 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
正解：A、B
解説：
the default behavior for iBGP is to propagate EBGP-learned prefixes without changing the next-hop. This can cause issues if the next-hop is not reachable via the IGP. One solution is to use the next-hop self command on R4, which will change the next-hop attribute to its own loopback address. This way, R5 can reach the next-hop via the IGP and install the route in its routing table.
Another solution is to add the external interface prefix (120.0.4.16/30) to the IGP routing tables of R4 and R5.
This will also make the next-hop reachable via the IGP and allow R5 to use the route. According to 2, this is a possible workaround for a pure IP network, but it may not work well for an MPLS network.
The reason why the route is being hidden is that R5 cannot reach the BGP next hop 10.0.0.1, which is the address of R1. R5 does not have a route to 10.0.0.0/24 in its routing table, and neither does R4. Therefore, R5 cannot resolve the BGP next hop and marks the route as hidden.
There are two solutions that will solve this problem:
Option A: On R4, create a policy to change the BGP next hop to itself and apply it to IBGP as an export policy. This way, R5 will receive the route with a next hop of 172.16.1.2, which is reachable via the IGP. This solution is also known as next-hop-self1.
Option B: Add the external interface prefix to the IGP routing tables. This way, R4 and R5 will learn a route to 10.0.0.0/24 via the IGP and be able to resolve the BGP next hop. This solution is also known as recursive lookup2.
Option C is not correct because adding the internal interface prefix to the BGP routing tables will not help R5 reach the BGP next hop 10.0.0.1.
Option D is not correct because changing the BGP next hop to 172.16.1.1 on R4 will not help R5 either, since R5 does not have a route to 172.16.1.1 in its routing table.
References: 1: Configuring Next-Hop-Self for IBGP Peers 2: Understanding Recursive Lookup
質問 # 47
Which two statements are correct regarding bootstrap messages that are forwarded within a PIM sparse mode domain? (Choose two.)
- A. Bootstrap messages are forwarded only to routers that explicitly requested the messages within the PIM sparse-mode domain
- B. Bootstrap messages distribute RP information dynamically during an RP election.
- C. Bootstrap messages are forwarded to all routers within a PIM sparse-mode domain.
- D. Bootstrap messages are used to notify which router is the PIM RP
正解：B、C
解説：
Bootstrap messages are PIM messages that are used to distribute rendezvous point (RP) information dynamically during an RP election. Bootstrap messages are sent by bootstrap routers (BSRs), which are routers that are elected to perform the RP discovery function for a PIM sparse-mode domain. Bootstrap messages contain information about candidate RPs and their multicast groups, as well as BSR priority and hash mask length. Bootstrap messages are forwarded to all routers within a PIM sparse-mode domain using hop-by-hop flooding.
質問 # 48 
Click the Exhibit button.
PE-1 and PE-2 are configured with LDP-signaled pseudowires to provide connectivity between CE-1 and CE-
2. You notice no connectivity exists between CE-1 and CE-2.
Referring to the exhibit, which two statements describe potential causes for this fault? (Choose two.)
- A. The VC IDs are mismatched.
- B. There is no LSP configured from PE-1 to PE-2.
- C. There is no LSP configured from PE-2 to PE-1.
- D. Interface ge-0/0/0 on PE-1 is down.
正解：A、C
質問 # 49
Refer to the Exhibit:
A network designer would like to advertise a single summary route from R4 to IS-IS level 2 neighbors as shown in the exhibit, but the configuration is not working.
Which three configuration changes will accomplish this task? (Choose three.)
- A. set policy-options policy-statement summary-v6 term DC-routes from route-filter 2001:dbS:a:fa00::/6l exact
- B. delete policy-options policy-statement summary-v6 term DC-routes from route-filter 2001:db5:a:fa00::
/61 longer - C. delete protocols isis export summary-v6
- D. set policy-options policy-statement summary-v6 term suppress then reject
- E. set protocols isis import summary-v6
正解：A、B、D
質問 # 50
Exhibit.
Referring to the exhibit, which path would traffic passing through R1 take to get to R4?
- A. R1 -> R4
- B. R1 -> R3 -> R4
- C. R1 -> R2 -> R3 -> R4
- D. R1 -> R2 -> R4
正解：D
解説：
The OSPF cost is carried in the LSAs that are exchanged within an OSPF area. When a router calculates the cost to a destination it uses the cost of the exit interface of each router in the path to the destination.
質問 # 51
You want to ensure that L1 IS-IS routers have only the most specific routes available from L2 IS-IS routers.
Which action accomplishes this task?
- A. Configure all routers to allow wide metrics.
- B. Configure all routers to be L1.
- C. Configure the ignore-attached-bit parameter on all L2 routers.
- D. Configure the ignore-attached-bit parameter on all L1 routers
正解：D
解説：
The attached bit is a flag in an IS-IS LSP that indicates whether a router is connected to another area or level (L2) of the network. By default, L2 routers set this bit when they advertise their LSPs to L1 routers, and L1 routers use this bit to select a default route to reach other areas or levels through L2 routers. However, this may result in suboptimal routing if there are multiple L2 routers with different paths to other areas or levels.
To ensure that L1 routers have only the most specific routes available from L2 routers, you can configure the ignore-attached-bit parameter on all L1 routers. This makes L1 routers ignore the attached bit and install all interarea routes learned from L2 routers in their routing tables.
質問 # 52
Exhibit
Referring to the exhibit, you are receiving the 192.168 0 0/16 route on both R3 and R4 from your EBGP neighbor You must ensure that R1 and R2 receive both BGP routes from the route reflector In this scenario, which BGP feature should you configure to accomplish this behavior?
- A. multihop
- B. add-path
- C. multipath
- D. route-target
正解：B
解説：
BGP add-path is a feature that allows the advertisement of multiple paths through the same peering session for the same prefix without the new paths implicitly replacing any previous paths. This behavior promotes path diversity and reduces multi-exit discriminator (MED) oscillations. BGP add-path is implemented by adding a path identifier to each path in the NLRI. The path identifier can be considered as something similar to a route distinguisher in VPNs, except that a path ID can apply to any address family. Path IDs are unique to a peering session and are generated for each network3. In this question, we have a route reflector (RR) that receives two routes for the same prefix (192.168.0.0/16) from an EBGP neighbor. By default, the RR will only advertise its best path to its clients (R1 and R2). However, we want R1 and R2 to receive both routes from the RR. To achieve this, we need to configure BGP add-path on the RR and enable it to send multiple paths for the same prefix to its clients.
質問 # 53
You are running a service provider network and must transport a customer's IPv6 traffic across your IPv4-based MPLS network using BGP. You have already configured mpls ipv6-tunneling on your PE routers.
Which two statements are correct about the BGP configuration in this scenario? (Choose two.)
- A. You must configure family inet6 unicast between PE routers.
- B. You must configure family inet6 labeled-unicast between PE routers.
- C. You must configure family inet6 unicast between PE and CE routers.
- D. You must configure family inet6 add-path between PE and CE routers.
正解：B、C
質問 # 54
Exhibit
You are running a service provider network and must transport a customer's IPv6 traffic across your IPv4-based MPLS network using BGP You have already configured mpis ipv6-tunneling on your PE routers.
Which two statements are correct about the BGP configuration in this scenario? (Choose two.)
- A. You must configure family inet6 unicast between PE routers.
- B. You must configure family inet6 labeled-unicast between PE routers.
- C. You must configure family inet6 unicast between PE and CE routers.
- D. You must configure family inet6 add-path between PE and CE routers.
正解：B、C
解説：
To transport IPv6 traffic over an IPv4-based MPLS network using BGP, you need to configure two address families: family inet6 labeled-unicast and family inet6 unicast. The former is used to exchange IPv6 routes with MPLS labels between PE routers, and the latter is used to exchange IPv6 routes without labels between PE and CE routers. The mpis ipv6-tunneling command enables the PE routers to encapsulate the IPv6 packets with an MPLS label stack and an IPv4 header before sending them over the MPLS network.
質問 # 55
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. To use this drop profile, you apply it directly to an interface.
- B. To use this drop profile, you reference it in a scheduler.
- C. The drop probability gradually increases from 20% to 60% as the queue level increases from 50% full to
75% full - D. The drop probability jumps immediately from 20% to 60% when the queue level reaches 75% full.
正解：B、C
解説：
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; } }
質問 # 56
Exhibit
Referring to the exhibit, a working L3VPN exists that connects VPN-A sites CoS is configured correctly to match on the MPLS EXP bits of the LSP, but when traffic is sent from Site-1 to Site-2, PE-2 is not classifying the traffic correctly What should you do to solve the problem?
- A. Set a static CoS value for the PE-1_to_PE-2 LSP
- B. Configure the explicit-null statement on PE-2
- C. Configure the explicit-null statement on PE-1.
- D. Configure VPN prefix mapping for the PE-1_to_PE-2 LSP
正解：C
解説：
The explicit-null statement enables the PE router to send an MPLS label with a value of 0 (explicit null) instead of an IP header for packets destined to the VPN customer sites. This allows the penultimate hop router (the router before the egress PE router) to preserve the EXP bits of the MPLS label and pass them to the egress PE router. The egress PE router can then use these EXP bits to classify the traffic according to the CoS policy2
. In this example, PE-1 should configure the explicit-null statement under [edit protocols mpls label-switched-path PE-1_to_PE-2] hierarchy level.
質問 # 57
Exhibit
Referring to the exhibit, which statement is correct?
- A. The vrf-target configuration will allow routes to be shared between CE-1 and CE-2.
- B. The vrf-target configuration will stop routes from being shared between CE-1 and CE-2.
- C. The route-distinguisher configuration will allow overlapping routes to be shared between CE-1 and CE-2.
- D. The route-diatinguisher configuration will stop routes from being shared between CE-1 and CE-2.
正解：C
解説：
The route distinguisher (RD) is a BGP attribute that is used to create unique VPN IPv4 prefixes for each VPN in an MPLS network. The RD is a 64-bit value that consists of two parts: an administrator field and an assigned number field. The administrator field can be an AS number or an IP address, and the assigned number field can be any arbitrary value chosen by the administrator. The RD is prepended to the IPv4 prefix to create a VPN IPv4 prefix that can be advertised across the MPLS network without causing any overlap or conflict with other VPNs. In this question, we have two PE routers (PE-1 and PE-2) that are connected to two CE devices (CE-1 and CE-2) respectively. PE-1 and PE-2 are configured with VRFs named Customer-A and Customer-B respectively.
質問 # 58
You are configuring a BGP signaled Layer 2 VPN across your MPLS enabled core network. In this scenario, which statement is correct?
- A. You must assign a unique site number to each attached site's configuration.
- B. You must use the same route-distinguiaher value on both PE devices.
- C. This type of VPN only supports Ethernet interfaces when connecting to CE devices.
- D. This type of VPN requires the support of the inet-vpn NLRI on all core BGP devices
正解：D
解説：
Explanation
BGP signaled Layer 2 VPN is a type of VPN that uses BGP to distribute VPN labels and information for Layer 2 connectivity between sites over an MPLS network. BGP signaled Layer 2 VPN requires the support of the l2vpn NLRI on all core BGP devices . The l2vpn NLRI is a new address family that carries Layer 2 VPN information such as the VPN identifier, the attachment circuit identifier, and the route distinguisher. The l2vpn NLRI is used for both auto-discovery and signaling of Layer 2 VPNs . In this scenario, we are configuring a BGP signaled Layer 2 VPN across an MPLS enabled core network. Therefore, we need to ensure that all core BGP devices support the l2vpn NLRI.
References: 1:
https://www.juniper.net/documentation/us/en/software/junos/vpn-l2/topics/concept/vpn-layer-2-overview.html
2:
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mp_l2_vpns/configuration/xe-16/mp-l2-vpns-xe-16-book/vpl
質問 # 59
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