Juniper JN0-351 Certification All-in-One Exam Guide May-2024
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Juniper JN0-351 Exam Syllabus Topics:
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NEW QUESTION # 37
You deployed a new EX Series switch with DHCP snooping enabled and you do not see any entries in the snooping databases for an interface. Which two Juniper configurations for that interface caused this issue?
(Choose two.)
- A. The interface is configured as a disabled port.
- B. MAC limiting is enabled on the interface.
- C. The interface is configured as a trunk port.
- D. Dynamic ARP inspection is enabled on the interface.
Answer: A,C
Explanation:
A is correct because the interface is configured as a disabled port. A disabled port does not forward any traffic, including DHCP packets. Therefore, DHCP snooping cannot learn any MAC addresses or lease information from a disabled port1.
C is correct because the interface is configured as a trunk port. By default, all trunk ports on the switch are trusted for DHCP snooping2. This means that DHCP snooping does not inspect or filter any DHCP packets received on a trunk port. Therefore, DHCP snooping does not add any entries to the snooping database for a trunk port2.
NEW QUESTION # 38
Which two statements correctly describe RSTP port roles? (Choose two.)
- A. The backup port is used as a backup for the root port.
- B. The alternate port is a standby port for an edge port.
- C. The designated port forwards data to the downstream network segment or device.
- D. The root port is responsible for forwarding data to the root bridge.
Answer: C,D
Explanation:
Explanation
In Rapid Spanning Tree Protocol (RSTP), there are several port roles that determine the behavior of the port in the spanning tree1.
Option A suggests that the designated port forwards data to the downstream network segment or device. This is correct because the designated port is the port on a network segment that has the best path to the root bridge1. It's responsible for forwarding frames towards the root bridge and sending configuration messages into its segment1.
Option D suggests that the root port is responsible for forwarding data to the root bridge. This is also correct because the root port is always the link directly connected to the root bridge, or the shortest path to the root bridge1. It's used to forward traffic towards the root bridge1.
Therefore, options A and D are correct.
NEW QUESTION # 39
You want to ensure traffic is routed through a GRE tunnel.
In this scenario, which two statements will satisfy this requirement? (Choose two.)
- A. BFD must be used on the stateless tunneling protocols.
- B. All intermediary devices must have a route to the tunnel endpoints.
- C. Tunnel endpoints must have a route that directs traffic into the tunnel.
- D. Keepalives must be used on stateless tunneling protocols.
Answer: B,C
Explanation:
Explanation
Option A is correct. For traffic to be sent through a GRE tunnel, there must be a route that directs the traffic into the tunnel. This is typically accomplished through the use of a static route or a dynamic routing protocol.
Option B is correct. All intermediary devices must have a route to the tunnel endpoints34. In real-world scenarios, the tunnel endpoints for a tunnel going over the Internet must have globally reachable internet addresses. Otherwise, intermediate routers in the Internet cannot forward the tunneled packets.
NEW QUESTION # 40
You are attempting to configure the initial two aggregated Ethernet interfaces on a router but there are no aggregated Ethernet interfaces available.
In this scenario, which configuration will enable these interfaces on this router?
- A.

- B.

- C.

- D.

Answer: D
Explanation:
Explanation
The correct answer to your question is
Option C shows the configuration of the statement, which defines the properties of the router chassis, such as the number of aggregated Ethernet interfaces, the number of FPCs, and the number of PICs1.
To enable aggregated Ethernet interfaces on a router, you need to specify the aggregated-devices statement under the chassis parameter to the desired number of interfaces2. For example, to enable two aggregated Ethernet interfaces, you can use the following configuration:
chassis { aggregated-devices { ethernet { device-count 2; } } }
Option C shows this configuration with the device-count set to 2, which will enable two aggregated Ethernet interfaces on the router. The other options do not show this configuration and will not enable any aggregated Ethernet interfaces on the router.
Therefore, option C is the correct answer to your question.
NEW QUESTION # 41
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. static route using the resolve feature
- B. generate route
- C. aggregate route
- D. static route using qualified next hops
Answer: C
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 # 42
Which statement is correct about controlling the routes installed by a RIB group?
- A. An import policy is applied to the RIB group.
- B. Only routes in the last table are installed.
- C. An export policy is applied to the RIB group.
- D. A firewall filter must be configured to install routes in the RIB groups.
Answer: A
Explanation:
Explanation
A RIB group is a configuration that allows a routing protocol to install routes into multiple routing tables in Junos OS. 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 or group. A RIB group can also include an import-policy statement, which specifies one or more policies to control which routes are imported into the destination routing table or group1.
An import policy is a policy statement that defines the criteria for accepting or rejecting routes from the source routing table. An import policy can also modify the attributes of the imported routes, such as preference, metric, or community. An import policy can be applied to a RIB group by using the import-policy statement under the [edit routing-options rib-groups] hierarchy level1.
Therefore, option A is correct, because an import policy is applied to the RIB group to control which routes are installed in the destination routing table or group. Option B is incorrect, because all routes in the source routing table are imported into the destination routing table or group, unless filtered by an import policy.
Option C is incorrect, because a firewall filter is not used to install routes in the RIB groups; a firewall filter is used to filter packets based on various criteria. Option D is incorrect, because an export policy is not applied to the RIB group; an export policy is applied to a routing protocol to control which routes are advertised to other devices.
References:
1: rib-groups | Junos OS | Juniper Networks
NEW QUESTION # 43
Exhibit
You are a network operator troubleshooting BGP connectivity.
Which two statements are correct about the output shown in the exhibit? (Choose two.)
- A. Peer 10.32.1.2 is configured for AS 63645.
- B. The routers are exchanging IPv4 routes.
- C. The R1 is configured for AS 65400.
- D. The BGP session is not established.
Answer: C,D
Explanation:
Explanation
Option B suggests that the BGP session is not established. This is correct because in the output, the state of the BGP session is shown as "Idle". In BGP, an "Idle" state means that the BGP session is not currently established1.
Option C suggests that R1 is configured for AS 65400. This is also correct because in the output, it's shown that the local AS number is 654001. The local AS number represents the Autonomous System (AS) number of the router on which you're checking the BGP session1.
NEW QUESTION # 44
Exhibit
Which command displays the output shown in the exhibit?
- A. show route forwarding-table family ethernet-switching
- B. show route forwarding-table
- C. show ethernet-switching table
- D. show ethernet-switching table extensive
Answer: C
Explanation:
The output shown in the exhibit is a brief display of the Ethernet switching table, which shows the learned Layer 2 MAC addresses for each VLAN and interface1.
The command show ethernet-switching table displays the Ethernet switching table with brief information, such as the destination MAC address, the VLAN name, the forwarding state, and the interface name1.
The command show route forwarding-table displays the routing table information for each protocol family, such as inet, inet6, mpls, iso, and so on2. It does not show the Ethernet switching table or the MAC addresses.
The command show ethernet-switching table extensive displays the Ethernet switching table with extensive information, such as the destination MAC address, the VLAN name, the forwarding state, the interface name, the VLAN index, and the tag type1. It shows more details than the brief output shown in the exhibit.
The command show route forwarding-table family ethernet-switching displays the routing table information for the ethernet-switching protocol family, whichshows the destination MAC address, the next-hop MAC address, and the interface name3. It does not show the VLAN name or the forwarding state.
NEW QUESTION # 45
Which two statements are correct about using firewall filters on EX Series switches? (Choose two.)
- A. You can deploy both stateless and stateful firewall filters on an EX Series switch.
- B. You can only apply firewall filters to Layer 2 traffic on an EX Series switch.
- C. You can apply firewall filters to both Layer 2 and Layer 3 traffic on an EX Series switch.
- D. You can deploy only stateless firewall filters on an EX Series switch.
Answer: C,D
Explanation:
A is correct because you can deploy only stateless firewall filters on an EX Series switch. A stateless firewall filter is a filter that evaluates each packet individually based on the header information, such as source and destination addresses, protocol, and port numbers1. A stateless firewall filter does not keep track of the state or context of a packet flow, such as the sequence number, flags, or sessioninformation1. EX Series switches support only stateless firewall filters, which are also called access control lists (ACLs) or packet filters2.
C is correct because you can apply firewall filters to both Layer 2 and Layer 3 traffic on an EX Series switch. Layer 2 traffic is traffic that is switched within a VLAN or a bridge domain, while Layer 3 traffic is traffic that is routed between VLANs or networks3. EX Series switches support three types of firewall filters: port (Layer 2) firewall filters, VLAN firewall filters, and router (Layer 3) firewall filters4. You can apply these filters to different interfaces and directions to control the traffic entering or exiting the switch.
NEW QUESTION # 46
Which two BGP attributes must be supported by all BGP implementations and must be included in every update? (Choose two.)
- A. MED
- B. community
- C. AS path
- D. next hop
Answer: C,D
Explanation:
Explanation
BGP attributes are properties that BGP uses for route advertisement, path selection, and loop prevention1. There are four categories of BGP attributes123:
Well-known mandatory: Must be recognized by all BGP routers, present in all BGP updates, and passed on to other BGP routers123.
Well-known discretionary: Supported by all BGP implementations, and are optionally included in BGP updates1.
Optional transitive: May not be supported by all implementations of BGP1.
Optional non-transitive: May not be supported by all implementations of BGP1.
The well-known mandatory attributes must be supported by all BGP implementations and must be included in every update123. These include the AS path and next hop attributes23. Therefore, options A and C are correct.
NEW QUESTION # 47
Exhibit.
Which router will become the OSPF BDR if all routers are powered on at the same time?
- A. R4
- B. R2
- C. R3
- D. R1
Answer: A
Explanation:
Explanation
OSPF DR/BDR election is a process that occurs on multi-access data links. It is intended to select two OSPF nodes: one to be acting as the Designated Router (DR), and another to be acting as the Backup Designated Router (BDR).The DR and BDR are responsible for generating network LSAs for the multi-access network and synchronizing the LSDB with other routers on the same network1.
The DR/BDR election is based on two criteria: the OSPF priority and the router ID. The OSPF priority is a value between 0 and 255 that can be configured on each interface participating in OSPF. The default priority is
1. A priority of 0 means that the router will not participate in the election and will never become a DR or BDR. The router with the highest priority will become the DR, and the router with the second highest priority will become the BDR. If there is a tie in priority, then the router ID is used as a tie-breaker. The router ID is a
32-bit number that uniquely identifies each router in an OSPF domain.It can be manually configured or automatically derived from the highest IP address on a loopback interface or any active interface2.
In this scenario, all routers have the same priority of 1, so the router ID will determine the outcome of the election. The router IDs are shown in the exhibit as RID values. The highest RID belongs to R4 (10.10.10.4), so R4 will become the DR. The second highest RID belongs to R3 (10.10.10.3), so R3 will become the BDR.
References:
1:OSPF DR/BDR Election: Process, Configuration, and Tuning2:OSPF Designated Router (DR) and Backup Designated Router (BDR)
NEW QUESTION # 48
Which three protocols support BFD? (Choose three.)
- A. LACP
- B. FTP
- C. OSPF
- D. BGP
- E. RSTP
Answer: A,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 # 49
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. MAC limiting
- B. voice VLAN
- C. DHCP snooping
- D. native VLAN
Answer: B
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 # 50
You are an operator for a network running 1S-IS. Two routers are failing to form an adjacency. What are two reasons for this problem? (Choose two.)
- A. The family iso configuration is missing from the adjacency interface.
- B. There are mismatched router IDs on the L2 routers.
- C. There is no configured ISO address on any IS-IS interface.
- D. There is a mismatched area ID between the L2 routers.
Answer: A,C
Explanation:
Explanation
The two reasons for the failure to form an adjacency in a network running IS-IS could be:
B: There is no configured ISO address on any IS-IS interface. IS-IS requires each router interface to have an ISO address configured. Without this address, the routers cannot form an adjacency1.
D: The family iso configuration is missing from the adjacency interface. The 'family iso' configuration is essential for IS-IS to function correctly. If this configuration is missing from the adjacency interface, it could prevent the formation of an adjacency1.
These explanations are based on the Enterprise Routing and Switching Specialist (JNCIS-ENT) documents and learning resources available at Juniper Networks23.
NEW QUESTION # 51
Exhibit.
What is the management IP address of the device shown in the exhibit?
- A. 128.0.0.1
- B. 172.23.12.100
- C. 172.23.11.10
- D. 10.210.20.233
Answer: B
Explanation:
Explanation
The management IP address of a device is the IP address that is used to access the device for configuration and monitoring purposes. It is usually assigned to a dedicatedmanagement interface that is separate from the data interfaces. The management interface can be accessed via SSH, Telnet, HTTP, or other protocols.
In the exhibit, the list of interfaces and their statuses shows that the management interface isme0. This interface has an admin status ofup, a protocol status ofinet, a local address of172.23.12.100/24, and a remote address ofunspecified. This means that the me0 interface is active, has an IPv4 address assigned, and is not connected to another device.
Therefore, the management IP address of the device shown in the exhibit is172.23.12.100.
References:
[Management Interfaces Overview] : [Displaying Interface Status Information]
NEW QUESTION # 52
What is a purpose of using a spanning tree protocol?
- A. to eliminate broadcast storms
- B. to tunnel Ethernet frames
- C. to route IP packets
- D. to look up MAC addresses
Answer: A
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 # 53
What are two characteristics of RSTP alternate ports? (Choose two.)
- A. RSTP alternate ports are active ports used to forward frames toward the root bridge.
- B. RSTP alternate ports block traffic while receiving superior BPDUs from a neighboring switch.
- C. RSTP alternate ports provide an alternate lower cost path to the root bridge.
- D. RSTP alternate ports provide an alternate higher cost path to the root bridge.
Answer: B,D
Explanation:
A is correct because RSTP alternate ports block traffic while receiving superior BPDUs from a neighboring switch. An alternate port is a backup port for a root port, which means it receives better BPDUs from another bridge than the current root port1. However, an alternate port does not forward any traffic, as it is in a discarding state2. It only listens to BPDUs and waits for the root port to fail. If the root port fails, the alternate port can immediately transition to a forwarding state and become the new root port1.
C is correct because RSTP alternate ports provide an alternate higher cost path to the root bridge. An alternate port is selected based on the same criteria as the root port, which are the lowest bridge ID, the lowest path cost, the lowest sender port ID, and the lowest receiver port ID3. However, an alternate port receives a higher cost BPDU than the root port, otherwise it would be the root port itself1. Therefore, an alternate port provides an alternate higher cost path to the root bridge than the root port.
NEW QUESTION # 54
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 ISPI . inet. 0 route table will be imported into the inet. 0 route table.
- B. The ISPI . inet. 0 route table will be completely overwritten by the inet. o route table.
- C. The inet. 0 route table will be completely overwritten by the ispi . inet. 0 route table.
- D. The inet. 0 route table will be imported into the ispi . inet. 0 route table.
Answer: D
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 # 55
Which two events cause a router to advertise a connected network to OSPF neighbors? (Choose two.)
- A. When an interface has the OSPF passive option enabled.
- B. When a static route to the 224.0.0.5 address is created.
- C. When an OSPF adjacency is established.
- D. When a static route to the 224.0.0.6 address is created.
Answer: B,C
Explanation:
A is correct because when an OSPF adjacency is established, a router will advertise a connected network to OSPF neighbors. An OSPF adjacency is a logical relationship between two routers that agree to exchange routing information using the OSPF protocol1. To establish an OSPF adjacency, the routers must be in the same area, have compatible parameters, and exchange hello packets1. Once an OSPF adjacency is formed, the routers will exchange database description (DBD) packets, which contain summaries of their link-state databases (LSDBs)1. The LSDBs include information about the connected networks and their costs2. Therefore, when an OSPF adjacency is established, a router will advertise a connected network to OSPF neighbors through DBD packets.
D is correct because when a static route to the 224.0.0.5 address is created, a router will advertise a connected network to OSPF neighbors. The 224.0.0.5 address is the multicast address for all OSPF routers3. A static route to this address can be used to send OSPF hello packets to all OSPF neighbors on a network segment3. This can be useful when the network segment does not support multicast or when the router does not have an IP address on the segment3. When a static route to the 224.0.0.5 address is created, the router will send hello packets to this address and establish OSPF adjacencies with other routers on the segment3. As explained above, once an OSPF adjacency is formed, the router will advertise a connected network to OSPF neighbors through DBD packets.
NEW QUESTION # 56
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