Juniper JN0-664 Service Provider Routing and Switching, Professional Exam JNCIP-SP Exam Practice Test

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Total 96 questions
Question 1

Exhibit

Referring to the exhibit, which three statements are correct about route 10 0 0.0/16 when using the default BGP advertisement rules'? (Choose three.)



Answer : A, C, E


Question 2

Which two statements describe PIM-SM? (Choose two)



Answer : A, D

PIM sparse mode (PIM-SM) is a multicast routing protocol that uses a pull model to deliver multicast traffic. In PIM-SM, routers with receivers send join messages to their upstream neighbors toward a rendezvous point (RP) or a source-specific tree (SPT). The RP or SPT acts as the root of a shared distribution tree for a multicast group. Traffic is only forwarded to routers that request to join the distribution tree by sending join messages. PIM-SM does not flood traffic to all routers or prune routers without receivers, as PIM dense mode does.


Question 3

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)



Answer : C, D

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


Question 4

After a recent power outage, your manager asks you to investigate ways to automatically reduce the impact caused by suboptimal routing in your OSPF and OSPFv3 network after devices reboot.

Which three configuration statements accomplish this task? (Choose three.)



Answer : A, C, E

To reduce the impact of suboptimal routing in OSPF and OSPFv3 after devices reboot, you can use the overload feature to prevent a router from being used as a transit router for a specified period of time. This allows the router to stabilize its routing table before forwarding traffic for other routers. To enable the overload feature, you need to do the following:

For OSPF, configure the overload statement under [edit protocols ospf] hierarchy level. You can also specify a timeout value in seconds to indicate how long the router should remain in overload state after it boots up. For example, set protocols ospf overload timeout 900 means that the router will be in overload state for 15 minutes after it boots up.

For OSPFv3, configure the overload statement under [edit protocols ospf3] hierarchy level. You can also specify a realm (ipv4-unicast or ipv6-unicast) and a timeout value in seconds to indicate how long the router should remain in overload state after it boots up for each realm. For example, set protocols ospf3 realm ipv4-unicast overload timeout 900 means that the router will be in overload state for 15 minutes after it boots up for IPv4 unicast routing.


Question 5

Refer to the exhibit.

Click the Exhibit button.

Referring to the exhibit, which two statements are true? (Choose two.)



Answer : C, D

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.**

**Reference**:

- 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)


Question 6

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.)



Answer : B, D

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.**

**Reference**:

- Juniper Networks Documentation on L2VPNs: [Configuring Layer 2 VPNs](https://www.juniper.net/documentation/en_US/junos/topics/task/configuration/layer-2-vpns-configuring.html)

- OSPF Configuration Guide: [Junos OS OSPF Configuration](https://www.juniper.net/documentation/en_US/junos/topics/concept/ospf-routing-overview.html)


Question 7

By default, which statement is correct about OSPF summary LSAs?



Answer : C

OSPF uses different types of LSAs to describe different aspects of the network topology. Type 1 LSAs are also known as router LSAs, and they describe the links and interfaces of a router within an area. Type 3 LSAs are also known as summary LSAs, and they describe routes to networks outside an area but within the same autonomous system (AS). By default, OSPF will summarize routes from Type 1 LSAs into Type 3 LSAs when advertising them across area boundaries .


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