Pass the Juniper JNCIS-ENT JN0-351 Questions and answers with Dumpstech

Both aggregate and generated routes would work, but the best choice is generated routes.

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 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 device 1 .  A virtual-router routing instance allows administrators to divide a device into multiple independent virtual routers, each with its own routing table 2 .

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.

According to the Juniper documentation 1 , the source and destination addresses of a GRE tunnel interface must be in different subnets. If they are in the same subnet, the router will not be able to route the GRE packets correctly. In the exhibit, the source and destination addresses are both in the 192.168.197.0/24 subnet, which is invalid for GRE tunneling. Therefore, the correct answer is D. References:  Configuring GRE Tunnel Interfaces | Junos OS

To isolate management traffic in a non-default routing-instance on Junos-based devices, you can use the  set system management-instance  and  set routing-instances mgmt_junos  commands 1 2 .

set system management-instance : This command associates the management interface (usually named fxp0 or em0 for Junos OS, or re0:mgmt-* or re1:mgmt-* for Junos OS Evolved) with the non-default virtual routing and forwarding (VRF) instance 1 .  After you configure the non-default management VRF instance, management traffic no longer has to share a routing table with other control traffic or protocol traffic 1 .

set routing-instances mgmt_junos : This command creates a new routing instance named  mgmt_junos .  The name of the dedicated management VRF instance is reserved and hardcoded as  mgmt_junos ; you cannot configure any other routing instance by the name  mgmt_junos 1 .

Therefore, options C and D are correct.  Options A and B are not correct because they attempt to assign an interface to the  mgmt_junos  routing instance, which is not necessary for isolating management traffic 1 .

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 information 1 .  This database is used to filter and validate DHCP messages from untrusted sources 1 .

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 attacks 1 . 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 database 1 .  The DHCP snooping feature relies on monitoring DHCP messages to build its database 1 , 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 database 1 , and Dynamic ARP inspection (DAI) uses the information stored in the DHCP snooping binding database but does not prevent entries from being created 1 .