Juniper JN0-664 Online Practice Questions and Exam Preparation

Juniper JN0-664 Online Questions & Answers

• Question 21:

  Which origin code is preferred by BGP?

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

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  Explanation/Reference:

  Prefer the route with the lower origin code.

  Routes learned from an IGP have a lower origin code than those learned from an exterior gateway protocol (EGP), and both have lower origin

  codes than incomplete routes (routes whose origin is unknown).

  https://www.juniper.net/documentation/us/en/software/junos/vpn-l2/bgp/topics/concept/routing-protocols-address-representation.html

• Question 22:

  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
  C. destination-based Remote Triggered Black Hole

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  Explanation/Reference:

  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.

• Question 23:

  Referring to the exhibit.

  

  Which two statements are true about the OSPF adjacency displayed in the exhibit? (Choose two.)

  A. There is a mismatch in the hello interval parameter between routers R1 and R2
  B. There is a mismatch in the dead interval parameter between routers R1 and R2.
  C. There is a mismatch in the OSPF hold timer parameter between routers R1 and R2.
  D. There is a mismatch in the poll interval parameter between routers R1 and R2.
  A. There is a mismatch in the hello interval parameter between routers R1 and R2
  B. There is a mismatch in the dead interval parameter between routers R1 and R2.

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  Explanation/Reference:

  The hello interval is the time interval between two consecutive hello packets sent by an OSPF router on an interface. The dead interval is the time interval after which a neighbor is declared down if no hello packets are received from it. These parameters must match between two OSPF routers for them to form an adjacency. In the exhibit, router R1 has a hello interval of 10 seconds and a dead interval of 40 seconds, while router R2 has a hello interval of 30 seconds and a dead interval of 120 seconds. This causes a mismatch and prevents them from becoming neighbors23.

• Question 24:

  Referring to the exhibit

  

  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 tra c from CE-1 on both links to PE-2 and PE-3. When CE-1 sends broadcast tra c. CE-2 receives it on only one of the multihomed links.

  Which EVPN route type enables this behavior?

  A. Type 2
  B. Type 4
  C. Type 1
  D. Type 3
  B. Type 4

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  Explanation/Reference:

  EVPN route type-4 is used for electing designated forwarder

• Question 25:

  Referring to the exhibit Which two statements are correct about the dual route re ectors within a cluster? (Choose two.)

  

  A. RR1 and RR2 must have the same duster ID to exchange routes learned from the client.
  B. RR1 and RR2 append the duster ID when advertising routes from dient to dient.
  C. RR1 and RR2 advertise routes learned from the clients to EBGP peers, using itself as the next hop.
  D. RR1 advertises routes from the client to RR2. using itself as the next hop.
  B. RR1 and RR2 append the duster ID when advertising routes from dient to dient.
  C. RR1 and RR2 advertise routes learned from the clients to EBGP peers, using itself as the next hop.

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  Explanation/Reference:

• Question 26:

  Referring to the exhibit.

  

  A network designer would like to create a summary route as shown in the exhibit, but the configuration is not working.

  Which three configuration changes will create a summary route? (Choose three.)

  A. set policy-options policy-statement leak-v6 term DC-routes then reject
  B. delete policy-options policy-statement leak-v6 term DC-routes from route-filter 2001:db9:a:fa00::/61 longer
  C. set policy--options policy-statement leak-v term DC--routes from route-filter 2001:db9:a:fa00::/61 exact
  D. delete protocols isis export summary-v6
  E. set protocols isis import summary-v6
  B. delete policy-options policy-statement leak-v6 term DC-routes from route-filter 2001:db9:a:fa00::/61 longer
  C. set policy--options policy-statement leak-v term DC--routes from route-filter 2001:db9:a:fa00::/61 exact
  D. delete protocols isis export summary-v6

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  Explanation/Reference:

  To create a summary route for IS-IS, you need to configure a policy statement that matches the prefixes to be summarized and sets the next-hop to discard. You also need to configure a summary-address statement under the IS-IS protocol hierarchy that references the policy statement. In this case, the policy statement leak-v6 is trying to match the prefix 2001:db9:a:fa00::/61 exactly, but this prefix is not advertised by any router in the network. Therefore, no summary route is created. To fix this, you need to delete the longer keyword from the route-filter term and change the prefix length to /61 exact. This will match any prefix that falls within the /61 range. You also need to delete the export statement under protocols isis, because this will export all routes that match the policy statement to other IS-IS routers, which is not desired for a summary route.

• Question 27:

  In which two ways does OSPF prevent routing loops in multi-area networks? (Choose two.)

  A. All areas are required to connect as a full mesh.
  B. The LFA algorithm prunes all looped paths within an area.
  C. All areas are required to connect to area 0.
  D. The SPF algorithm prunes looped paths within an area.
  C. All areas are required to connect to area 0.
  D. The SPF algorithm prunes looped paths within an area.

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  Explanation/Reference:

  OSPF is an interior gateway protocol that uses link-state routing to exchange routing information among routers within a single autonomous system. OSPF prevents routing loops in multi-area networks by using two methods: area hierarchy and SPF algorithm. Area hierarchy is the concept of dividing a large OSPF network into smaller areas that are connected to a backbone area (area 0). This reduces the amount of routing information that each router has to store and process, and also limits the scope of link-state updates within each area. All areas are required to connect to area 0 either directly or through virtual links. SPF algorithm is the method that OSPF uses to calculate the shortest path to each destination in the network based on link-state information. The SPF algorithm runs on each router and builds a shortest-path tree that represents the topology of the network from the router's perspective. The SPF algorithm prunes looped paths within an area by choosing only one best path for each destination. References: https://www.juniper.net/documentation/us/en/software/junos/ospf/topics/concept/ospf-area-overview.html https://www.juniper.net/documentation/us/en/software/junos/ospf/topics/concept/ospf-spf-algorithm-overview.html

• Question 28:

  You must alter class-of-service values in packets on the outbound interface of an edge router. In this scenario, which CoS component allows you to accomplish this task?

  A. output policer
  B. scheduler
  C. rewrite rules
  D. forwarding classes
  C. rewrite rules

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  Explanation/Reference:

  Rewrite rules in the context of CoS typically involve modifying or rewriting certain fields of packets as they traverse through a router. This can include changing the value of the Differentiated Services Code Point (DSCP) or the EXP bits in the MPLS header, among other things. By configuring rewrite rules, you can manipulate the CoS values of packets before they are transmitted out of the outbound interface.

• Question 29:

  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
  B. If a point-to-point interface is in both L1 and L2, separate hello messages are sent for each level.
  D. If a broadcast interface is in both L1 and L2, separate hello messages are sent for each level

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  Explanation/Reference:

  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.

• Question 30:

  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 used to notify which router is the PIM RP
  D. Bootstrap messages are forwarded to all routers within a PIM sparse-mode domain.
  B. Bootstrap messages distribute RP information dynamically during an RP election.
  C. Bootstrap messages are used to notify which router is the PIM RP

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  Explanation/Reference: