Juniper JN0-636 Exam Dumps Questions and Answers

According to the Juniper documentation, filter-based forwarding (FBF) is a technique that allows the SRX Series device to forward packets based on firewall filter rules, rather than the default routing table1. FBF can be used to implement policy-based routing, load balancing, or traffic engineering2. To deploy FBF on the SRX Series device for incoming traffic sourced from the 10.10.100.0/24 network, the following steps are required:

• You must create a forwarding-type routing instance. A forwarding-type routing instance is a special type of routing instance that is used for FBF. It does not have any interfaces or routing protocols associated with it, but it has its own routing table that can be populated by static routes, RIB groups, or routing policies3. You can create a forwarding-type routing instance by using the following command:

set routing-instances instance-type forwarding

• You must create and apply a firewall filter that matches on the source address 10.10.100.0/24 and then sends this traffic to your routing instance. A firewall filter is a set of rules that can match on various packet attributes, such as source and destination addresses, ports, protocols, and so on. You can use the then routing-instance action to specify the routing instance that the packet should be forwarded to4. You can create and apply a firewall filter by using the following commands:

set firewall family inet filter term from source-address 10.10.100.0/24 set firewall family inet filter term then routing-instance  set interfaces unit family inet filter input

• You must create a RIB group that adds interface routes to your routing instance. A RIB group is a mechanism that allows you to import routes from one routing table to another. You can use a RIB group to add the interface routes of the ingress interface to the routing table of the forwarding-type routing instance. This will ensure that the SRX device can forward the packets to the correct next hop based on the destination address5. You can create a RIB group by using the following commands:

set routing-options rib-groups import-rib inet.0 set routing-options rib-groups import-rib .inet.0 set routing-instances routing-options instance-import

The following steps are not required or incorrect:

• You do not need to create a VRF-type routing instance. A VRF-type routing instance is a type of routing instance that is used for virtual routing and forwarding. It allows you to create multiple logical routers on the same physical device, each with its own interfaces, routing protocols, and routing tables. VRF-type routing instances are typically used for VPNs, MPLS, or network segmentation. However, they are not necessary for FBF, which can be achieved with a forwarding-type routing instance.
• You do not need to create and apply a firewall filter that matches on the destination address 10.10.100.0/24 and then sends this traffic to your routing instance. This would be redundant and unnecessary, as the destination address of the incoming traffic is already determined by the routing table of the forwarding-type routing instance. Moreover, this would create a loop, as the traffic would be sent back to the same routing instance that it came from.

References: 1: Filter-Based Forwarding Overview 2: Configuring Filter-Based Forwarding 3: forwarding (Routing Instances) 4: routing-instance (Firewall Filter Action) 5: Configuring RIB Groups : [vrf (Routing Instances)]

According to the exhibit, which is a configuration snippet of the SRX Series device, the global mode for the device is set to switching mode. This means that the device is operating as a Layer 2 switch and does not apply any security policies to the traffic between hosts in the same broadcast domain1. Therefore, the traffic between two hosts in the same broadcast domain are not matching any security policies.

To solve this problem, the user should change the global mode to transparent bridge mode. This means that the device will operate as a Layer 2 transparent bridge and apply security policies to the traffic between hosts in the same broadcast domain2. This will allow the user to enforce security policies based on the source and destination IP addresses, ports, and protocols of the traffic.

To change the global mode to transparent bridge mode, the user should use the following command:

set protocols l2-learning global-mode transparent-bridge

This command will set the global mode for the SRX Series device as Layer 2 transparent bridge mode. After changing the mode, the user must reboot the device for the configuration to take effect2.

References: 1: global-mode (Protocols) 2: Configuring Layer 2 Transparent Mode

You want traffic to avoid the flow daemon for administrative tasks. In this scenario, the two stateless services that are available with selective stateless packet-based services are:

• A. Layer 2 switching. Layer 2 switching is a stateless service that forwards packets based on the MAC addresses of the source and destination hosts. Layer 2 switching does not require any routing or flow processing, and can be performed by the Packet Forwarding Engine (PFE) of the SRX Series device. You can use selective stateless packet-based services to enable Layer 2 switching for traffic that matches a stateless firewall filter. The firewall filter must have the packet-mode action modifier to bypass the flow daemon1.
• B. IPv4 routing. IPv4 routing is a stateless service that forwards packets based on the IP addresses of the source and destination hosts. IPv4 routing does not require any flow processing, and can be performed by the PFE of the SRX Series device. You can use selective stateless packet-based services to enable IPv4 routing for traffic that matches a stateless firewall filter. The firewall filter must have the packet-mode action modifier to bypass the flow daemon1.

The other options are incorrect because:

• C. IPsec. IPsec is a stateful service that provides security and encryption for IP packets. IPsec requires flow processing, and cannot be performed by the PFE of the SRX Series device. You cannot use selective stateless packet-based services to enable IPsec for traffic that matches a stateless firewall filter. The firewall filter cannot have the packet-mode action modifier to bypass the flow daemon2.
• D. IPv6 routing. IPv6 routing is a stateful service that forwards packets based on the IP addresses of the source and destination hosts. IPv6 routing requires flow processing, and cannot be performed by the PFE of the SRX Series device. You cannot use selective stateless packet-based services to enable IPv6 routing for traffic that matches a stateless firewall filter. The firewall filter cannot have the packet-mode action modifier to bypass the flow daemon3.

References:

• Selective Stateless Packet-Based Services Overview
• IPsec VPN Overview
• IPv6 Overview