JN0-664 Exam - Service Provider - Professional (JNCIP-SP)

NEW QUESTION 1
What is the correct order of packet flow through configurable components in the Junos OS CoS features?

• A. Multifield Classifier -> Behavior Aggregate Classifier -> Input Policer -> Forwarding Policy Options -> Fabric Scheduler -> Output Policer -> Rewrite Marker -> Scheduler/Shaper/RED
• B. Behavior Aggregate Classifier -> Multifield Classifier -> Input Policer -> Forwarding Policy Options -> Fabric Scheduler -> Output Policer -> Scheduler/Shaper/RED -> Rewrite Marker
• C. Behavior Aggregate Classifier -> Input Policer -> Multifield Classifier -> Forwarding Policy Options -> Fabric Scheduler -> Output Policer -> Scheduler/Shaper/RED -> Rewrite Marker
• D. Behavior Aggregate Classifier -> Multifield Classifier -> Input Policer -> Forwarding Policy Options -> Fabric Scheduler -> Scheduler/Shaper/RED -> Output Policer -> Rewrite Marker

Answer: C

Explanation:
The correct order of packet flow through configurable components in the Junos OS CoS features is as follows:
✑ Behavior Aggregate Classifier: This component uses a single field in a packet header to classify traffic into different forwarding classes and loss priorities based on predefined or user-defined values.
✑ Input Policer: This component applies rate-limiting and marking actions to incoming traffic based on the forwarding class and loss priority assigned by the classifier.
✑ Multifield Classifier: This component uses multiple fields in a packet header to classify traffic into different forwarding classes and loss priorities based on user- defined values and filters.
✑ Forwarding Policy Options: This component applies actions such as load balancing, filtering, or routing to traffic based on the forwarding class and loss priority assigned by the classifier.
✑ Fabric Scheduler: This component schedules traffic across the switch fabric based on the forwarding class and loss priority assigned by the classifier.
✑ Output Policer: This component applies rate-limiting and marking actions to outgoing traffic based on the forwarding class and loss priority assigned by the classifier.
✑ Scheduler/Shaper/RED: This component schedules, shapes, and drops traffic at the egress interface based on the forwarding class and loss priority assigned by the classifier.
✑ Rewrite Marker: This component rewrites the code-point bits of packets leaving an interface based on the forwarding class and loss priority assigned by the classifier.

NEW QUESTION 2
Which origin code is preferred by BGP?

• A. Internal
• B. External
• C. Incomplete
• D. Null

Answer: C

Explanation:
BGP uses several attributes to select the best path for a destination prefix. One of these attributes is origin, which indicates how BGP learned about a route. The origin attribute can have one of three values: IGP, EGP, or Incomplete. IGP means that the route was originated by a network or aggregate statement within BGP or by redistribution from an IGP into BGP. EGP means that the route was learned from an external BGP peer (this value is obsolete since BGP version 4). Incomplete means that the route was learned by some other means, such as redistribution from a static route into BGP. BGP prefers routes with lower origin values, so Incomplete is preferred over EGP, which is preferred over IGP.

NEW QUESTION 3
Exhibit

Which two statements about the output shown in the exhibit are correct? (Choose two.)

• A. The PE is attached to a single local site.
• B. The connection has not flapped since it was initiated.
• C. There has been a VLAN ID mismatch.
• D. The PE router has the capability to pop flow labels

Answer: AD

Explanation:
According to 1 and2, BGP Layer 2 VPNs use BGP to distribute endpoint provisioning information and set up pseudowires between PE devices. BGP uses the Layer 2 VPN (L2VPN) Routing Information Base (RIB) to store endpoint provisioning information, which is updated each time any Layer 2 virtual forwarding instance (VFI) is configured. The prefix and path information is stored in the L2VPN database, which allows BGP to make decisions about the best path.
In the output shown in the exhibit, we can see some information about the L2VPN RIB and the pseudowire state. Based on this information, we can infer the following statements:
✑ The PE is attached to a single local site. This is correct because the output shows only one local site ID (1) under the L2VPN RIB section. A local site ID is a unique identifier for a site within a VPLS domain. If there were multiple local sites attached to the PE, we would see multiple local site IDs with different prefixes.
✑ The connection has not flapped since it was initiated. This is correct because the output shows that the uptime of the pseudowire is equal to its total uptime (1w6d). This means that the pseudowire has been up for one week and six days without any interruption or flap.
✑ There has been a VLAN ID mismatch. This is not correct because the output shows that the remote and local VLAN IDs are both 0 under the pseudowire state section. A VLAN ID mismatch occurs when the remote and local VLAN IDs are different, which can cause traffic loss or misdelivery. If there was a VLAN ID mismatch, we would see different values for the remote and local VLAN IDs.
✑ The PE router has the capability to pop flow labels. This is correct because the output shows that the flow label pop bit is set under the pseudowire state section. The flow label pop bit indicates that the PE router can pop (remove) the MPLS flow label from the packet before forwarding it to the CE device. The flow label is an optional MPLS label that can be used for load balancing or traffic engineering purposes.

NEW QUESTION 4
Which two statements are correct about VPLS tunnels? (Choose two.)

• A. LDP-signaled VPLS tunnels only support control bit 0.
• B. LDP-signaled VPLS tunnels use auto-discovery to provision sites
• C. BGP-signaled VPLS tunnels can use either RSVP or LDP between the PE routers.
• D. BGP-signaled VPLS tunnels require manual provisioning of sites.

Answer: BC

Explanation:
VPLS is a Layer 2 VPN technology that allows multiple sites to connect over a shared IP/MPLS network as if they were on the same LAN. VPLS tunnels can be signaled using either Label Distribution Protocol (LDP) or Border Gateway Protocol (BGP). LDP-signaled VPLS tunnels use auto-discovery to provision sites, meaning that PE routers can automatically discover other PE routers that belong to the same VPLS instance

NEW QUESTION 5
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. The drop probability gradually increases from 20% to 60% as the queue level increases from 50% full to 75% full
• C. To use this drop profile, you reference it in a scheduler.
• D. To use this drop profile, you apply it directly to an interface.

Answer: BC

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 6
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, create a policy to change the BGP next hop to itself and apply it to IBGP as an export policy
• B. Add the external interface prefix to the IGP routing tables
• 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

Answer: AB

Explanation:
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 to2, this is a possible workaround for a pure IP network, but it may not work well for an MPLS network.

NEW QUESTION 7
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 2 routes to advertise MAC address and IP address pairs learned using ARP snooping
• D. EVPN uses Type 3 routes to join a multicast tree to flood traffic.

Answer: CD

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 8
Which two statements about IS-IS are correct? (Choose two.)

• A. PSNPs are flooded periodically.
• B. PSNPs contain only descriptions of LSPs.
• C. CSNPs are flooded periodically
• D. CSNPs contain only descriptions of LSPs.

Answer: BC

Explanation:
IS-IS is an interior gateway protocol that uses link-state routing to exchange routing information among routers within a single autonomous system. IS-IS uses two types of packets to synchronize link-state databases among routers: Link State Packets (LSPs) and Partial Sequence Number Packets (PSNPs). LSPs contain information about the state and cost of links in the network, and are flooded periodically throughout the network. PSNPs are used to acknowledge receipt of LSPs and request retransmission of missing or corrupted LSPs. PSNPs contain only descriptions of LSPs, such as their sequence numbers and checksums3. IS-IS also uses another type of packet called Complete Sequence Number Packets (CSNPs), which are used to summarize the entire link-state database at regular intervals or when a new adjacency is formed. CSNPs are flooded periodically throughout the network and contain only descriptions of LSPs4. Therefore, PSNPs contain only descriptions of LSPs and CSNPs are flooded periodically. References: 3: https://www.juniper.net/documentation/us/en/software/junos/routing-
policy/topics/concept/routing-policy-is-is-partial-sequence-number-packet-psnp.html 4: https://www.juniper.net/documentation/us/en/software/junos/routing-policy/topics/concept/routing-policy-is-is-complete-sequence-number-packet-csnp.html

NEW QUESTION 9
Exhibit

Referring to the exhibit, CE-1 is providing NAT services for the hosts at Site 1 and you must provide Internet access for those hosts
Which two statements are correct in this scenario? (Choose two.)

• A. You must configure a static route in the main routing instance for the 10 1 2.0/24 prefix that uses the VPN-A.inet.0 table as the next hop
• B. You must configure a static route in the main routing instance for the 203.0.113.1/32 prefix that uses the VPN-A.inet.0 table as the next hop.
• C. You must configure a RIB group on PE-1 to leak a default route from the inet.0 table to the VPN-A.inet.0 table.
• D. You must configure a RIB group on PE-1 to leak the 10 1 2.0/24 prefix from the VPN- A.inet.0 table to the inet.0 table.

Answer: AB

Explanation:
To provide Internet access for the hosts at Site 1, you need to configure static routes in the main routing instance on PE-1 that point to the VPN-A.inet.0 table as the next hop. This allows PE-1 to forward traffic from the Internet to CE-1 using MPLS labels and vice versa. You need to configure two static routes: one for the 10.1.2.0/24 prefix that represents the private network of Site 1, and one for the 203.0.113.1/32 prefix that represents the public IP address of CE-1.

NEW QUESTION 10
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 the ignore-attached-bit parameter on all L2 routers.
• B. Configure all routers to allow wide metrics.
• C. Configure all routers to be L1.
• D. Configure the ignore-attached-bit parameter on all L1 routers

Answer: D

Explanation:
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.

NEW QUESTION 11
An interface is configured with a behavior aggregate classifier and a multifield classifier How will the packet be processed when received on this interface?

• A. The packet will be discarded.
• B. The packet will be processed by the BA classifier first, then the MF classifier.
• C. The packet will be forwarded with no classification changes.
• D. The packet will be processed by the MF classifier first, then the BA classifier.

Answer: C

Explanation:
behavior aggregate (BA) classifiers and multifield (MF) classifiers are two types of classifiers that are used to assign packets to a forwarding class and a loss priority based on different criteria. The forwarding class determines the output queue for a packet. The loss priority is used by a scheduler to control packet discard during periods of congestion.
A BA classifier maps packets to a forwarding class and a loss priority based on a fixed- length field in the packet header, such as DSCP, IP precedence, MPLS EXP, or IEEE 802.1p CoS bits. A BA classifier is computationally efficient and suitable for core devices that handle high traffic volumes. A BA classifier is useful if the traffic comes from a trusted source and the CoS value in the packet header is trusted.
An MF classifier maps packets to a forwarding class and a loss priority based on multiple fields in the packet header, such as source address, destination address, protocol type, port number, or VLAN ID. An MF classifier is more flexible and granular than a BA classifier and can match packets based on complex filter rules. An MF classifier is suitable for edge devices that need to classify traffic from untrusted sources or rewrite packet headers.
You can configure both a BA classifier and an MF classifier on an interface. If you do this, the BA classification is performed first and then the MF classification. If the two classification results conflict, the MF classification result overrides the BA classification result.
Based on this information, we can infer the following statements:
✑ The packet will be discarded. This is not correct because the packet will not be discarded by the classifiers unless it matches a filter rule that specifies discard as an action. The classifiers only assign packets to a forwarding class and a loss priority based on their match criteria.
✑ The packet will be processed by the BA classifier first, then the MF classifier. This is correct because if both a BA classifier and an MF classifier are configured on an interface, the BA classification is performed first and then the MF classification. If they conflict, the MF classification result overrides the BA classification result.
✑ The packet will be forwarded with no classification changes. This is not correct because the packet will be classified by both the BA classifier and the MF classifier if they are configured on an interface. The final classification result will determine which output queue and which discard policy will be applied to the packet.
✑ The packet will be processed by the MF classifier first, then the BA classifier. This is not correct because if both a BA classifier and an MF classifier are configured on an interface, the BA classification is performed first and then the MF classification. If they conflict, the MF classification result overrides the BA classification result.

NEW QUESTION 12
Exhibit

A network is using IS-IS for routing.
In this scenario, why are there two TLVs shown in the exhibit?

• A. There are both narrow and wide metric devices in the topology
• B. The interface specified a metric of 100 for L2.
• C. Wide metrics have specifically been requested
• D. Both IPv4 and IPv6 are being used in the topology

Answer: A

Explanation:
TLVs are tuples of (Type, Length, Value) that can be advertised in IS-IS packets. TLVs can carry different kinds of information in the Link State Packets (LSPs). IS- IS supports both narrow and wide metrics for link costs. Narrow metrics use a single octet to encode the link cost, while wide metrics use three octets. Narrow metrics have a maximum value of 63, while wide metrics have a maximum value of 16777215. If there are both narrow and wide metric devices in the topology, IS-IS will advertise two TLVs for each link: one with the narrow metric and one with the wide metric. This allows backward compatibility with older devices that only support narrow metrics12.

NEW QUESTION 13
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. This type of VPN only supports Ethernet interfaces when connecting to CE devices.
• C. This type of VPN requires the support of the inet-vpn NLRI on all core BGP devices
• D. You must use the same route-distinguiaher value on both PE devices.

Answer: C

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 devices1. 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 VPNs2. 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/vpls-bgp-signaling-l2vpn- inter-as-option-a.html

NEW QUESTION 14
Which two statements are correct about IS-IS interfaces? (Choose two.)

• A. If a broadcast interface is in both L1 and L2, one combined hello message is sent for both levels.
• B. If a point-to-point interface is in both L1 and L2, separate hello messages are sent for each level.
• C. If a point-to-point interface is in both L1 and L2, one combined hello message is sent for both levels.
• D. If a broadcast interface is in both L1 and L2, separate hello messages are sent for each level

Answer: BD

Explanation:
IS-IS supports two levels of routing: Level 1 (intra-area) and Level 2 (interarea). An IS-IS router can be either Level 1 only, Level 2 only, or both Level 1 and Level 2. A router that is both Level 1 and Level 2 is called a Level 1-2 router. A Level 1-2 router sends separate hello messages for each level on both point-to-point and broadcast interfaces1. A point-to-point interface provides a connection between a single source and a single destination. A broadcast interface behaves as if the router is connected to a LAN.

NEW QUESTION 15
By default, which statement is correct about OSPF summary LSAs?

• A. All Type 2 and Type 7 LSAs will be summanzed into a single Type 5 LSA
• B. The area-range command must be installed on all routers.
• C. Type 3 LSAs are advertised for routes in Type 1 LSAs.
• D. The metric associated with a summary route will be equal to the lowest metric associated with an individual contributing route

Answer: C

Explanation:
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 .

NEW QUESTION 16
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 family inet labeled-unicast hierarchy, add the explicit null parameter.
• B. Under the protocols ospf hierarchy, add the traffic-engineering parameter.
• C. Under the family inet labeled-unicast hierarchy, add the resolve-vpn parameter.
• D. Under the protocols mpls hierarchy, add the traffic-engineering parameter

Answer: C

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 17
You are asked to protect your company's customers from amplification attacks. In this scenario, what is Juniper's recommended protection method?

• A. ASN prepending
• B. BGP FlowSpec
• C. destination-based Remote Triggered Black Hole
• D. unicast Reverse Path Forwarding

Answer: C

Explanation:
amplification attacks are a type of distributed denial-of-service (DDoS) attack that exploit the characteristics of certain protocols to amplify the traffic sent to a victim. For example, an attacker can send a small DNS query with a spoofed source IP address to a DNS server, which will reply with a much larger response to the victim. This way, the attacker can generate a large amount of traffic with minimal resources.
One of the methods to protect against amplification attacks is destination-based Remote Triggered Black Hole (RTBH) filtering. This technique allows a network operator to drop traffic destined to a specific IP address or prefix at the edge of the network, thus preventing it from reaching the victim and consuming bandwidth and resources. RTBH filtering can be implemented using BGP to propagate a special route with a next hop of 192.0.2.1 (a reserved address) to the edge routers. Any traffic matching this route will be discarded by the edge routers.

NEW QUESTION 18
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 10 wins the DIS election over a router with a priority of 1.
• B. A router with a priority of 1 wins the DIS election over a router with a priority of 10.
• 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.

Answer: AD

Explanation:
In IS-IS, a designated intermediate system (DIS) is a router that is elected on a multi-access network segment (such as Ethernet) to perform some functions on behalf of other routers on the same segment. A DIS is responsible for sending network link-state advertisements (LSPs), which describe all the routers attached to the network. These LSPs are flooded throughout a single area. A DIS also generates pseudonode LSPs, which represent the multi-access network as a single node in the link-state database. A DIS election is based on the priority value configured on each router’s interface connected to the multi-access network. The priority value ranges from 0 to 127, with higher values indicating higher priority. The router with the highest priority becomes the DIS for the area (Level 1, Level 2, or both). If routers have the same priority, then the router with the highest MAC address is elected as the DIS. By default, routers have a priority value of 64. On a multi-access network, each router only forms an adjacency to the DIS, not to every other router on the segment. This reduces the amount of hello packets and LSP

NEW QUESTION 19
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