Juniper JN0-351 Dumps

The default MAC age-out timer on an EX Series switch is 300 seconds12. The MAC age-out timer is the maximum time that an entry can remain in the MAC table before it “ages out,” or is removed31. This configuration can influence efficiency of network resource use by affecting the amount of traffic that is flooded to all interfaces1. When traffic is received for MAC addresses no longer in the Ethernet routing table, the router floods the traffic to all interfaces1.

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

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)]