Juniper JN0-351 Practice Test - Questions Answers, Page 6

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.

The exhibit shows the output of the commandshow ip bgp, which displays information about the BGP routes in the routing table1. The output shows two routes for the destination 192.168.10.0/24, one from R1 and one from R2.

The route from R1 has a local preference of 200, while the route from R2 has a local preference of 100.Local preference is a BGP attribute that indicates the degree of preference for a route within an autonomous system (AS)2.A higher local preference means a more preferred route2.

BGP uses a best path selection algorithm to choose the best route for each destination among multiple paths.The algorithm compares different attributes of the routes in a specific order of precedence3.The first attribute that is compared is weight, which is a Cisco-specific attribute that is local to the router3.If the weight is equal or not set, the next attribute that is compared is local preference3.

In this case, both routes have the same weight of 0, which means that they are learned from external BGP (eBGP) peers3. Therefore, the next attribute that is compared is local preference.Since R1's route has a higher local preference than R2's route, it is chosen as the best path and installed in the routing table3. The other attributes, such as origin code and AS path, are not considered in this case.

Option A is correct.The storm control feature is enabled in the factory-default configuration on EX Series switches12.On EX2200, EX3200, EX3300, EX4200, and EX6200 switches, the factory default configuration enables storm control for broadcast and unknown unicast traffic on all switch interfaces2.On EX4300 switches, the factory default configuration enables storm control on all Layer 2 switch interfaces1.

Option B is incorrect.The storm control feature does not require a special license on EX Series switches34.

Option C is incorrect. There's no information available that suggests the storm control feature is not supported on aggregate Ethernet interfaces.

Option D is incorrect.The storm control configuration applies to traffic at the ingress of an interface5, not just between the forwarding and control plane.

Bis correct because the loops do not exist is one of the conditions that are verified by the receiving router to ensure that the received BGP route is valid.A loop in BGP means that a route has been advertised by the same AS more than once, which can cause routing instability and inefficiency1.To prevent loops, BGP uses the AS-path attribute, which lists the AS numbers that a route has traversed from the origin to the destination2.The receiving router checks the AS-path attribute of the received route and discards it if it finds its own AS number in the list2. This way, BGP avoids accepting routes that contain loops.

Cis correct because the next hop is reachable is one of the conditions that are verified by the receiving router to ensure that the received BGP route is valid.The next hop is the IP address of the next router that is used to forward packets to the destination network3.The receiving router checks the next hop attribute of the received route and verifies that it has a valid route to reach it3.If the next hop is not reachable, the received route is not usable and is rejected by the receiving router3. This way, BGP ensures that only feasible routes are accepted.

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.

Ais 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.

Dis 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.

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.

The DHCP snooping feature in Juniper Networks' EX Series switches works by building a binding database that maps the IP address, MAC address, lease time, binding type, VLAN number, and interface information1.This database is used to filter and validate DHCP messages from untrusted sources1.

However, there are certain conditions that could prevent entries from being automatically created in the snooping database for an interface:

MAC limiting: If MAC limiting is enabled on the interface, it could potentially interfere with the operation of DHCP snooping.MAC limiting restricts the number of MAC addresses that can be learned on a physical interface to prevent MAC flooding attacks1. This could inadvertently limit the number of DHCP clients that can be learned on an interface, thus preventing new entries from being added to the DHCP snooping database.

Static IP address: If the device connected to the interface is configured with a static IP address, it will not go through the DHCP process and therefore will not have an entry in the DHCP snooping database1.The DHCP snooping feature relies on monitoring DHCP messages to build its database1, so devices with static IP addresses that do not send DHCP messages will not have their information added.

Therefore, options B and C are correct.Options A and D are not correct because performing a DHCPRELEASE would simply remove an existing entry from the database1, and Dynamic ARP inspection (DAI) uses the information stored in the DHCP snooping binding database but does not prevent entries from being created1.

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 clear the 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.