[Mar 05, 2024] JN0-351 Sample with Accurate & Updated Questions
JN0-351 Exam Info and Free Practice Test | DumpsActual
Juniper JN0-351 Exam Syllabus Topics:
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NEW QUESTION # 23
What is a purpose of using a spanning tree protocol?
- A. to look up MAC addresses
- B. to route IP packets
- C. to tunnel Ethernet frames
- D. to eliminate broadcast storms
Answer: D
Explanation:
A broadcast storm is a network condition where a large number of broadcast packets are sent and received by multiple devices, causing congestion and performance degradation1. A broadcast storm can occur when there are loops in the network topology, meaning that there are multiple paths between two devices2.
A spanning tree protocol is a network protocol that prevents loops from being formed when switches or bridges are interconnected via multiple paths. It does this by creating a logical tree structure that spans all the devices in the network, and disabling or blocking the links that are not part of the tree, leaving a single active path between any two devices3.
By eliminating loops, a spanning tree protocol also eliminates broadcast storms, as broadcast packets will not be forwarded endlessly along the looped paths. Instead, broadcast packets will be sent only along the tree structure, reaching each device once and avoiding congestion3.
NEW QUESTION # 24
Exhibit.
The ispi _ inet. 0 route table has currently no routes in it.
What will happen when you commit the configuration shown on the exhibit?
- A. The inet. 0 route table will be completely overwritten by the ispi . inet. 0 route table.
- B. The inet. 0 route table will be imported into the ispi . inet. 0 route table.
- C. The ISPI . inet. 0 route table will be imported into the inet. 0 route table.
- D. The ISPI . inet. 0 route table will be completely overwritten by the inet. o route table.
Answer: B
Explanation:
Explanation
The configuration shown in the exhibit is an example of a routing instance of type virtual-router. A routing instance is a collection of routing tables, interfaces, and routing protocol parameters that create a separate routing domain on a Juniper device1. A virtual-router routing instance allows administrators to divide a device into multiple independent virtual routers, each with its own routing table2.
The configuration also includes a rib-group statement, which is used to import routes from one routing table to another. A rib-group consists of an import-rib statement, which specifies the source routing table, and an export-rib statement, which specifies the destination routing table.
In this case, the rib-group name is inet-to-ispi, and the import-rib statement specifies inet.0 as the source routing table. The export-rib statement specifies ispi.inet.0 as the destination routing table. This means that the routes from inet.0 will be imported into ispi.inet.0.
Therefore, the correct answer is B. The inet.0 route table will be imported into the ispi.inet.0 route table.
References:
1: Routing Instances Overview 2: Virtual Routing Instances : [rib-group (Routing Options)]
NEW QUESTION # 25
Exhibit
Referring to the exhibit, which statement is correct?
- A. The local device is the root bridge for this RSTP topology.
- B. The local device is using a bridge priority of 4k.
- C. The root bridge is using a bridge priority of 4k.
- D. The root bridge has not been elected for this RSTP topology.
Answer: A
Explanation:
Explanation
In a Rapid Spanning Tree Protocol (RSTP) topology, the root bridge is determined by the switch with the lowest bridge priority value12. If all switches have the same priority, then the root bridge is assigned to the switch whose MAC address's hex value is the lowest2. The default bridge priority value is 3276832. However, without the actual exhibit, it's difficult to definitively determine which device is the root bridge. But based on the options provided, if we assume that the local device has a lower bridge priority or a lower MAC address than other devices in the network, then it could be considered as the root bridge for this RSTP topology45.
NEW QUESTION # 26
Exhibit
Your ISP is announcing a default route to both R1 and R2. You want your network routers to forward all Internet traffic through the R1 device Which BGP attribute would you use?
- A. origin
- B. local preference
- C. MED
- D. next-hop
Answer: B
Explanation:
Explanation
The BGP attribute that you would use to forward all Internet traffic through the R1 device is the local preference1.
The local preference is an attribute that is used within an autonomous system (AS) and exchanged between iBGP routers1. It is used to select an exit point from the AS1. The path with the highest local preference is preferred1. By setting a higher local preference for the routes received from R1, you can make R1 the preferred exit point for all Internet traffic1.
NEW QUESTION # 27
You are receiving multiple BGP routes from an upstream neighbor and only want to advertise a single summarized prefix to your internal OSPF neighbors. This route should only be advertised when you are receiving these BGP routes from this neighbor.
In this scenario, which type of route should you create?
- A. aggregate route
- B. generate route
- C. static route using the resolve feature
- D. static route using qualified next hops
Answer: A
Explanation:
Explanation
In this scenario, you should create an 1. Aggregate routes are used for advertising summarized network prefixes1. They help minimize the number of routing tables in an IP network by consolidating selected multiple routes into a single route advertisement1. This approach is in contrast to non-aggregation routing, in which every routing table contains a unique entry for each route1.
Therefore, option A is correct. Options B, C, and D are not correct because:
Static route using the resolve feature: This type of route uses the resolve feature to install a static route in the routing table only if a specific condition is met1. However, it does not provide the capability to summarize multiple routes into a single prefix.
Generate route: This type of route generates a route that is always present in the routing table and can be used to summarize routes. However, it does not have the capability to only advertise the route when specific BGP routes are being received from a neighbor1.
Static route using qualified next hops: This type of route allows for the specification of multiple next-hop addresses for a static route1. However, it does not provide the capability to summarize multiple routes into a single prefix.
NEW QUESTION # 28
Which three protocols support BFD? (Choose three.)
- A. FTP
- B. BGP
- C. OSPF
- D. LACP
- E. RSTP
Answer: B,C,D
Explanation:
Explanation
BFD is a protocol that can be used to quickly detect failures in the forwarding path between two adjacent routers or switches. BFD can be integrated with various routing protocols and link aggregation protocols to provide faster convergence and fault recovery.
According to the Juniper Networks documentation, the following protocols support BFD on Junos OS devices1:
BGP: BFD can be used to monitor the connectivity between BGP peers and trigger a session reset if a failure is detected. BFD can be configured for both internal and external BGP sessions, as well as for IPv4 and IPv6 address families2.
OSPF: BFD can be used to monitor the connectivity between OSPF neighbors and trigger a state change if a failure is detected. BFD can be configured for both OSPFv2 and OSPFv3 protocols, as well as for point-to-point and broadcast network types3.
LACP: BFD can be used to monitor the connectivity between LACP members and trigger a link state change if a failure is detected. BFD can be configured for both active and passive LACP modes, as well as for static and dynamic LAGs4.
Other protocols that support BFD on Junos OS devices are:
IS-IS: BFD can be used to monitor the connectivity between IS-IS neighbors and trigger a state change if a failure is detected. BFD can be configured for both level 1 and level 2 IS-IS adjacencies, as well as for point-to-point and broadcast network types.
RIP: BFD can be used to monitor the connectivity between RIP neighbors and trigger a route update if a failure is detected. BFD can be configured for both RIP version 1 and version 2 protocols, as well as for IPv4 and IPv6 address families.
VRRP: BFD can be used to monitor the connectivity between VRRP routers and trigger a priority change if a failure is detected. BFD can be configured for both VRRP version 2 and version 3 protocols, as well as for IPv4 and IPv6 address families.
The protocols that do not support BFD on Junos OS devices are:
RSTP: RSTP is a spanning tree protocol that provides loop prevention and rapid convergence in layer 2 networks. RSTP does not use BFD to detect link failures, but relies on its own hello mechanism that sends BPDU packets every 2 seconds by default.
FTP: FTP is an application layer protocol that is used to transfer files between hosts over a TCP connection. FTP does not use BFD to detect connection failures, but relies on TCP's own retransmission and timeout mechanisms.
References:
1: [Configuring Bidirectional Forwarding Detection] 2: [Configuring Bidirectional Forwarding Detection for BGP] 3: [Configuring Bidirectional Forwarding Detection for OSPF] 4: [Configuring Bidirectional Forwarding Detection for Link Aggregation Control Protocol] : [Configuring Bidirectional Forwarding Detection for IS-IS] : [Configuring Bidirectional Forwarding Detection for RIP] : [Configuring Bidirectional Forwarding Detection for VRRP] : [Understanding Rapid Spanning Tree Protocol] : [Understanding FTP]
NEW QUESTION # 29
What is the default keepalive time for BGP?
- A. 90 seconds
- B. 60 seconds
- C. 10 seconds
- D. 30 seconds
Answer: B
Explanation:
Explanation
The default keepalive time for BGP is 60 seconds1. The keepalive time is the interval at which BGP sends keepalive messages to maintain the connection with its peer1. If the keepalive message is not received within the hold time, the connection is considered lost1. By default, the hold time is three times the keepalive time, which is 180 seconds1.
NEW QUESTION # 30
What are two reasons for creating multiple areas in OSPF? (Choose two.)
- A. to increase the number of adjacencies in the backbone
- B. to reduce LSA flooding across the network
- C. to increase the size of the LSDB
- D. to reduce the convergence time
Answer: B,D
Explanation:
Explanation
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.
NEW QUESTION # 31
Two routers share the same highest priority and start time.
- A. The router with the highest router ID becomes the DR
- B. In this situation, what is evaluated next when determining the designated router? The router with the lowest router ID become the DR.
- C. The routers perform another DR election.
- D. The router with the highest MAC address become the DR
Answer: A
Explanation:
According to the OSPF protocol, the designated router (DR) is the router that acts as the focal point for exchanging routing information on a multi-access network segment, such as a LAN1. The DR election process is based on the following criteria, in order of precedence1:
The router with the highest OSPF priority becomes the DR. The default priority is 1, and a priority of 0 means the router will not participate in the election.
If there is a tie in priority, the router with the highest router ID becomes the DR. The router ID is a 32-bit number that uniquely identifies a router in an OSPF domain. It can be manually configured or automatically derived from the highest IP address of a loopback interface or a physical interface.
If there is a tie in router ID, the router that was first to become an OSPF neighbor becomes the DR.
In your scenario, two routers share the same highest priority and start time. This means that they have equal chances of becoming the DR based on the first and third criteria. Therefore, the second criterion will be used to break the tie, which is the router ID. The router with the highest router ID will become the DR, and the other router will become the backup designated router (BDR), which is ready to take over the role of DR if it fails1.
NEW QUESTION # 32
Which statement about aggregate routes is correct?
- A. Aggregate routes are used for advertising summarized network prefixes.
- B. Aggregate routes are always preferred over more specific routes, even when the specific routes have a better path.
- C. Aggregate routes are automatically generated for all of the subnets in a routing table.
- D. Aggregate routes can only be used for static routing but not for dynamic routing protocols.
Answer: A
Explanation:
Explanation
Aggregate routes are used for advertising summarized network prefixes12. They help minimize the number of routing tables in an IP network by consolidating selected multiple routes into a single route advertisement1. This approach is in contrast to non-aggregation routing, in which every routing table contains a unique entry for each route1.
Therefore, option D is correct. Options A, B, and C are not correct because:
Aggregate routes can be used with both static routing and dynamic routing protocols1.
Aggregate routes are not automatically generated for all of the subnets in a routing table. They need to be manually configured1.
Aggregate routes are not always preferred over more specific routes. The route selection process in Junos OS considers several factors, including route preference and metric, before determining the active route1.
NEW QUESTION # 33
You are asked to connect an IP phone and a user computer using the same interface on an EX Series switch.
The traffic from the computer does not use a VLAN tag, whereas the traffic from the IP phone uses a VLAN tag.
Which feature enables the interface to receive both types of traffic?
- A. voice VLAN
- B. DHCP snooping
- C. native VLAN
- D. MAC limiting
Answer: A
Explanation:
Explanation
The feature that enables an interface on an EX Series switch to receive both untagged traffic (from the computer) and tagged traffic (from the IP phone) is the voice VLAN12.
The voice VLAN feature in EX-series switches enables access ports to accept both data (untagged) and voice (tagged) traffic and separate that traffic into different VLANs12. This allows the switch to differentiate between voice and data traffic, ensuring that voice traffic can be treated with a higher priority12. Therefore, option D is correct.
NEW QUESTION # 34
You implemented the MAC address limit feature with the shutdown action on all interfaces on your switch.
In this scenario, which statement is correct when a violation occurs?
- A. By default, you must manually clear the violation for the interface to send and receive traffic again.
- B. By default, devices that are learned before the violation occurs are still allowed to send and receive traffic through the specific interface.
- C. By default, the interface will continue to send and receive traffic for all connected devices after a violation has occurred.
- D. By default, the violation will automatically be cleared after 300 seconds and the interface will resume sending and receiving traffic for all learned devices.
Answer: A
Explanation:
Explanation
When the MAC address limit feature with the shutdown action is implemented on a switch, if a violation occurs, the interface is disabled and a system log entry is generated1. If the switch has been configured with the port-error-disable statement, the disabled interface recovers automatically upon expiration of the specified disable timeout1. However, if the switch has not been configured for auto-recovery from port error disabled conditions, you must manually clearthe violation by running the clear ethernet-switching port-error command for the interface to send and receive traffic again1. This explanation is based on the Enterprise Routing and Switching Specialist (JNCIS-ENT) documents and learning resources available at Juniper Networks1.
NEW QUESTION # 35
Which two types of tunnels are able to be created on all Junos devices? (Choose two.)
- A. GRE
- B. STP
- C. IP-IP
- D. IPsec
Answer: A,D
Explanation:
Explanation
Junos devices support various types of tunnels for different purposes12.
Option B is correct. Generic Routing Encapsulation (GRE) is a tunneling protocol that can encapsulate a wide variety of network layer protocols inside virtual point-to-point links over an Internet Protocol network1. Junos devices support GRE tunnels1.
Option D is correct. IPsec (Internet Protocol Security) is a protocol suite for securing Internet Protocol (IP) communications by authenticating and encrypting each IP packet of a communication session1. Junos devices support IPsec tunnels1.
Option A is incorrect. Spanning Tree Protocol (STP) is not a type of tunnel. It's a network protocol designed to prevent loops in a bridged Ethernet local area network2.
Option C is incorrect. While Junos devices do support IP-IP (also known as IP tunneling), it's not supported on all Junos devices1.
NEW QUESTION # 36
In RSTP, which three port roles are associated with the discarding state? (Choose three.)
- A. backup
- B. alternate
- C. root
- D. designated
- E. disabled
Answer: A,B,E
Explanation:
Explanation
In Rapid Spanning Tree Protocol (RSTP), there are several port roles that determine the behavior of the port in the spanning tree123. The roles include root, designated, alternate, backup, and disabled123.
The discarding state is associated with the backup, alternate, and disabled roles123. In a stable topology with consistent port roles throughout the network, RSTP ensures that every root port and designated port immediately transition to the forwarding state while all alternate and backup ports are always in the discarding state2. Disabled ports are also in the discarding state3.
Therefore, options B, C, and D are correct.
NEW QUESTION # 37
Exhibit.
You have configured the four EX Series switches with RSTP, as shown in the exhibit. You discover that whenever a link between switches goes up or down, the switches take longer than expected for RSTP to converge, using the default settings.
In this scenario, which action would solve the delay in RSTP convergence?
- A. The force-version must be removed.
- B. The bridge priority for EX-4 must be set at 4000.
- C. The max-age must be increased to 20
- D. The hello-time must be increased.
Answer: A
Explanation:
The exhibit shows the configuration of RSTP on EX-4, which has the command force-version stp. This command forces the switch to use the legacy STP protocol instead of RSTP, even though the switch supports RSTP1. This means that EX-4 will not be able to take advantage of the faster convergence and enhanced features of RSTP, such as edge ports, link type, and proposal/agreement sequence2.
The other switches in the network are likely to be running RSTP, as it is the default protocol for EX Series switches3. Therefore, there will be a compatibility issue between EX-4 and the other switches, which will result in longer convergence times and suboptimal performance. The switch will also generate a warning message that says "Warning: STP version mismatch with neighbor" when it receives a BPDU from a RSTP neighbor1.
To solve this problem, the force-version command must be removed from EX-4, so that it can run RSTP natively and interoperate with the other switches in the network. This will enable faster convergence and better stability for the network topology. To remove the command, you can use the delete protocols rstp force-version command in configuration mode1.
NEW QUESTION # 38
Which two statements are correct about generated routes? (Choose two.)
- A. Generated routes appear in the routing table as static routes
- B. Generated routes show a next hop in the routing table.
- C. Generated routes cannot be redistributed into dynamic routing protocols.
- D. Generated routes require a contributing route.
Answer: B,D
Explanation:
A is correct because generated routes require a contributing route. A contributing route is a route that matches the destination prefix of the generated route and has a valid next hop1. A generated route is only installed in the routing table if there is at least one contributing route available2. This ensures that the generated route is reachable and useful. If there is no contributing route, the generated route is not added to the routing table2.
B is correct because generated routes show a next hop in the routing table. A generated route inherits the next hop of its primary contributing route, which is the most preferred route among all the contributing routes2. The next hop of the generated route can be either an IP address or an interface name, depending on the type of the contributing route2. The next hop of the generated route can also be modified by a routing policy3.
NEW QUESTION # 39
You want to use filter-based forwarding (FBF) on your Internet peering router to load-balance traffic to two directly connected ISPs based on the source address.
Which two statements are correct in this scenario? (Choose two.)
- A. RIB groups are used to copy routes from the inet. o routing table.
- B. FBF uses the forwarding routing instance type.
- C. FBF uses the no-forwarding routing instance type.
- D. RIB groups are used to hide routes in the inet. 0 routing table.
Answer: A,B
Explanation:
Option B is correct. Filter-based forwarding (FBF), also known as Policy Based Routing (PBR), uses the forwarding routing instance type12.
Option C is correct. Routing Information Base (RIB) groups are used to copy routes from one routing table to another34. In the context of FBF, RIB groups can be used to copy routes from the inet.0 routing table34.
Option A is incorrect. FBF does not use the no-forwarding routing instance type15.
Option D is incorrect. RIB groups are not used to hide routes in the inet.0 routing table34. They are used to share or copy routes between different routing tables34.
NEW QUESTION # 40
Exhibit
Your BGP neighbors, one in the USA and one in France, are not establishing a connection with each other.
Referring to the exhibit, which statement is correct?
- A. The BFD liveness must be configured on the BGP neighbor.
- B. The BFD liveness must be configured on the BGP group.
- C. The BFD liveness is set too low.
- D. The BFD liveness is set too high.
Answer: A
Explanation:
Explanation
The exhibit shows the configuration of BFD liveness detection for BGP at the global level, which applies to all BGP neighbors by default1. However, this configuration does not specify the session mode, which determines whether BFD uses single-hop or multihop mode to communicate with a neighbor2.
For single-hop BGP neighbors, which are directly connected on the same subnet, the session mode can be either automatic or single-hop. For multihop BGPneighbors, which are not directly connected and require multiple hops to reach, the session mode must be multihop2.
Since your BGP neighbors are in different countries, they are likely to be multihop neighbors. Therefore, you need to configure the session mode as multihop for each neighbor individually at the [edit protocols bgp group group-name neighbor address bfd-liveness-detection] hierarchy level2. For example:
protocols { bgp { group usa { neighbor 192.0.2.1 { bfd-liveness-detection { session-mode multihop; } } } group france { neighbor 198.51.100.1 { bfd-liveness-detection { session-mode multihop; } } } } } If you do not configure the session mode for multihop neighbors, BFD will use the default mode of automatic, which will try to use single-hop mode and fail to establish a BFD session with the remote neighbor2. This will prevent BGP from using BFD to detect liveliness and failover.
Therefore, the answer B is correct, as you need to configure the BFD liveness detection on the BGP neighbor level with the appropriate session mode for multihop neighbors.
NEW QUESTION # 41
Which two statements about redundant trunk groups on EX Series switches are correct? (Choose two.)
- A. Redundant trunk groups use spanning tree to provide loop-free redundant uplinks.
- B. Layer 2 control traffic is permitted on the secondary link.
- C. If the active link fails, then the secondary link automatically takes over.
- D. Redundant trunk groups load balance traffic across two designated uplink interfaces.
Answer: B,C
Explanation:
C is correct because Layer 2 control traffic is permitted on the secondary link of a redundant trunk group (RTG) on EX Series switches. Layer 2 control traffic includes protocols such as LLDP, LACP, and STP, which are used to exchange information and coordinate actions between switches1. According to the Juniper Networks documentation2, Layer 2 control traffic is allowed to pass through both the active and the secondary links of an RTG, but data traffic is only forwarded through the active link. This allows the switches to maintain their Layer 2 adjacencies and monitor the link status on both links.
D is correct because if the active link fails, then the secondary link automatically takes over in an RTG on EX Series switches. An RTG consists of two trunk links: an active or primary link, and a secondary or backup link2. The active link is used to forward data traffic, while the secondary link is in standby mode. If the active link fails or becomes unavailable, the secondary link immediately transitions to a forwarding state and takes over the data traffic without waiting for normal STP convergence2. This provides fast recovery and redundancy for the network.
NEW QUESTION # 42
You have two OSPF routers forming an adjacency. R1 has a priority of 32 and a router ID of 192.168.1.2. R2 has a priority of 64 and a router ID of 192.168.1.1. The routers were started at the same time and all other OSPF settings are the default settings.
Which statement is correct in this scenario?
- A. At least three routers are required for a DR/BDR election
- B. R1 will be the BDR.
- C. R2 will be the BDR.
- D. Router IDs must match for an adjacency to form.
Answer: B
Explanation:
Explanation
In OSPF, the Designated Router (DR) and Backup Designated Router (BDR) are elected based on the priority of the routers1. The router with the highest priority becomes the DR, and the router with the second highest priority becomes the BDR1. If there is a tie in priority, then the router with the highest Router ID is chosen1.
In this scenario, R2 has a higher priority (64) than R1 (32), so R2 will become the DR1. Since R1 has the second highest priority, it will become the BDR1. Therefore, option D is correct.
NEW QUESTION # 43
You need to configure a LAG between your switches. In this scenario, which two statements are correct?
(Choose two.)
- A. Member links are not required to be contiguous ports.
- B. Member links are required to be contiguous ports.
- C. Duplex and speed settings are required to match on both participating devices.
- D. Duplex and speed settings are not required to match on both participating devices.
Answer: A,C
Explanation:
B is correct because duplex and speed settings are required to match on both participating devices. According to the Juniper Networks documentation1, all the interfaces in a LAG must have the same speed and be in full-duplex mode. This ensures that the LAG can operate as a single logical link without any performance or compatibility issues.
C is correct because member links are not required to be contiguous ports. According to the Juniper Networks documentation2, you can group any Ethernet interfaces on a switch into a LAG, regardless of their physical location or slot number. This provides flexibility and scalability for configuring LAGs on switches.
NEW QUESTION # 44
You are asked to connect an IP phone and a user computer using the same interface on an EX Series switch.
The traffic from the computer does not use a VLAN tag, whereas the traffic from the IP phone uses a VLAN tag.
Which feature enables the interface to receive both types of traffic?
- A. voice VLAN
- B. DHCP snooping
- C. native VLAN
- D. MAC limiting
Answer: A
Explanation:
Explanation
The feature that enables an interface on an EX Series switch to receive both untagged traffic (from the computer) and tagged traffic (from the IP phone) is the voice VLAN12.
The voice VLAN feature in EX-series switches enables access ports to accept both data (untagged) and voice (tagged) traffic and separate that traffic into different VLANs12. This allows the switch to differentiate between voice and data traffic, ensuring that voice traffic can be treated with a higher priority12. Therefore, option D is correct.
NEW QUESTION # 45
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