Juniper JN0-351 Online Practice Questions and Exam Preparation

Juniper JN0-351 Online Questions & Answers

• Question 1:

  By default, how long will a learned MAC address be retained in the bridge table on an EX Series switch?

  A. 600 seconds
  B. 3600 seconds
  C. 300 seconds
  D. 1800 seconds
  C. 300 seconds

• Question 2:

  You are asked to create a new firewall filter to evaluate Layer 3 traffic that is being sent between VLANs. In this scenario, which two statements are correct? (Choose two.)

  A. You should create a family Ethernet-switching firewall filter with the appropriate match criteria and actions.
  B. You should apply the firewall filter to the appropriate VLAN.
  C. You should create a family inet firewall filter with the appropriate match criteria and actions.
  D. You should apply the firewall filter to the appropriate IRB interface.
  C. You should create a family inet firewall filter with the appropriate match criteria and actions.
  D. You should apply the firewall filter to the appropriate IRB interface.

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  Explanation/Reference:

  A firewall filter is a configuration that defines the rules that determine whether to forward or discard packets at specific processing points in the packet flow. A firewall filter can also modify the attributes of the packets, such as priority, marking, or logging. A firewall filter can be applied to various interfaces, protocols, or routing instances on a Juniper device1. A firewall filter has a family attribute, which specifies the type of traffic that the filter can evaluate. The family attribute can be one of the following: inet, inet6, mpls, vpls, iso, or ethernet-switching2. The family inet firewall filter is used to evaluate IPv4 traffic, which is the most common type of Layer 3 traffic on a network. To create a family inet firewall filter, you need to specify the appropriate match criteria and actions for each term in the filter. The match criteria can include various fields in the IPv4 header, such as source address, destination address, protocol, port number, or DSCP value. The actions can include accept, discard, reject, count, log, policer, or next term3. To apply a firewall filter to Layer 3 traffic that is being sent between VLANs, you need to apply the filter to the appropriate IRB interface. An IRB interface is an integrated routing and bridging interface that provides Layer 3 functionality for a VLAN on a Juniper device. An IRB interface has an IP address that acts as the default gateway for the hosts in the VLAN. An IRB interface can also participate in routing protocols and forward packets to other VLANs or networks4. Therefore, option C is correct, because you should create a family inet firewall filter with the appropriate match criteria and actions. Option D is correct, because you should apply the firewall filter to the appropriate IRB interface. Option A is incorrect, because you should not create a family ethernet-switching firewall filter with the appropriate match criteria and actions. A family ethernet-switching firewall filter is used to evaluate Layer 2 traffic on a Juniper device. A family ethernet-switching firewall filter can only match on MAC addresses or VLAN IDs, not on IP addresses or protocols5. Option B is incorrect, because you should not apply the firewall filter to the appropriate VLAN. A VLAN is a logical grouping of hosts that share the same broadcast domain on a Layer 2 network. A VLAN does not have an IP address or routing capability. A firewall filter cannot be applied directly to a VLAN; it must be applied to an interface that belongs to or connects to the VLAN6. References:

  1: Firewall Filters Overview 2: Configuring Firewall Filters 3: Configuring Firewall Filter Match Conditions and Actions 4: Understanding Integrated Routing and Bridging Interfaces 5: Configuring Ethernet-Switching Firewall Filters 6: Understanding VLANs

• Question 3:

  You are configuring an IS-IS IGP network and do not see the IS-IS adjacencies established. In this scenario, what are two reasons for this problem? (Choose two.)

  A. MTU is not at least 1492 bytes.
  B. IP subnets are not a /30 address.
  C. The Level 2 routers have mismatched areas.
  D. The lo0 interface is not included as an IS-IS interface.
  A. MTU is not at least 1492 bytes.
  D. The lo0 interface is not included as an IS-IS interface.

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  Explanation/Reference:

  Option A suggests that the MTU is not at least 1492 bytes. This is correct because IS-IS requires a minimum MTU of 1492 bytes to establish adjacencies1. If the MTU is less than this, IS-IS adjacencies will not be established1.

  Option D suggests that the lo0 interface is not included as an IS-IS interface. This is also correct because the loopback interface (lo0) is typically used as the router ID in IS-IS1. If the loopback interface is not included in IS-IS, it could prevent

  IS-IS adjacencies from being established1.

  Therefore, options A and D are correct.

• Question 4:

  What are two reasons for creating multiple areas in OSPF? (Choose two.)

  A. to reduce the convergence time
  B. to increase the number of adjacencies in the backbone
  C. to increase the size of the LSDB
  D. to reduce LSA flooding across the network
  A. to reduce the convergence time
  D. to reduce LSA flooding across the network

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  Explanation/Reference:

  Option A is correct. Creating multiple areas in OSPF can help to reduce the convergence time . This is because changes in one area do not affect other areas, so fewer routers need to run the SPF algorithm in response to a change.

  Option D is correct. Creating multiple areas in OSPF can help to reduce Link State Advertisement (LSA) flooding across the network. This is because LSAs are not flooded out of their area of origin.

• Question 5:

  Which two statements are true about high availability on Junos devices? (Choose two.)

  A. BFD is faster at detecting failures than default GRE or OSPF timers.
  B. NSR is independent of helper routers to assist the routing platform in restoring routing protocol information.
  C. NSR is dependent on helper routers to assist the routing platform in restoring routing protocol information.
  D. BFD is slower at detecting failures than default GRE or OSPF timers.
  A. BFD is faster at detecting failures than default GRE or OSPF timers.
  B. NSR is independent of helper routers to assist the routing platform in restoring routing protocol information.

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  Explanation/Reference:

  https://www.juniper.net/documentation/en_US/junos/topics/concept/nsr- overview.html

• Question 6:

  You are running a Virtual Chassis with nonstop routing enabled. You want to confirm that the BGP routing table synchronization has completed on the backup Routing Engine.

  Which command will show you this information?

  A. show task replication
  B. show bgp summary
  C. show bgp neighbor
  D. show bgp replication
  D. show bgp replication

• Question 7:

  What types of authentication are supported in Junos for OSPF?

  A. Simple password
  B. MD5 checksum
  C. Hitless key chain of MD5 keys/checksums
  D. All of the above
  D. All of the above

• Question 8:

  Which two statements about BPDU protection are correct? (Choose two.)

  A. By default, you must manually clear a BPDU error condition when using BPDU protection.
  B. BPDU protection prevents unauthorized switches from connecting to and participating in your spanning tree topology.
  C. By default, BPDU protection prevents the root bridge from communicating with other STP members unless it receives a superior BPDU first.
  D. BPDU protection requires that STP or RSTP is configured on the switch.
  A. By default, you must manually clear a BPDU error condition when using BPDU protection.
  B. BPDU protection prevents unauthorized switches from connecting to and participating in your spanning tree topology.

• Question 9:

  Which two statements about Layer 2 firewall filters are correct? (Choose two.)

  A. You can apply only one firewall filter term per filter.
  B. You can apply only one input filter per VLAN.
  C. You can apply multiple firewall filter terms per filter.
  D. You can apply multiple input filters per VLAN.
  B. You can apply only one input filter per VLAN.
  C. You can apply multiple firewall filter terms per filter.

• Question 10:

  Which two statements about a unified ISSU are correct? (Choose two.)

  A. It requires that Bidirectional Forwarding Detection be disabled.
  B. It requires that graceful Routing Engine switchover be enabled.
  C. It is only supported on platforms with redundant control planes.
  D. It is only supported on platforms with redundant power supplies.
  B. It requires that graceful Routing Engine switchover be enabled.
  C. It is only supported on platforms with redundant control planes.