Juniper Updated JN0-636 Exam Questions and Answers by boris

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)]

 You are connecting two remote sites to your corporate headquarters site. You must ensure that traffic passes through the corporate headquarters. In this scenario, the VPN that should be used is:

• D. Hub-and-spoke IPsec VPN with the corporate firewall acting as the hub device. A hub-and-spoke IPsec VPN is a type of VPN that connects multiple remote sites to a central site, or hub, over a public network. The hub site acts as a gateway for the remote sites and provides security and routing services. The remote sites, or spokes, communicate with each other through the hub site. The hub site and the spoke sites use IPsec tunnels to encrypt and authenticate the traffic between them. A hub-and-spoke IPsec VPN is suitable for connecting two remote sites to your corporate headquarters site, because it allows you to control the traffic flow and enforce security policies at the hub site. The corporate firewall can act as the hub device and provide IPsec VPN services to the remote sites1.

The other options are incorrect because:

• A. Full mesh IPsec VPNs with tunnels between all sites. A full mesh IPsec VPN is a type of VPN that connects every site to every other site over a public network. Each site has an IPsec tunnel with every other site, forming a mesh topology. A full mesh IPsec VPN provides direct and secure communication between any pair of sites, but it also requires a large number of IPsec tunnels and complex configuration. A full mesh IPsec VPN is not suitable for connecting two remote sites to your corporate headquarters site, because it does not ensure that traffic passes through the corporate headquarters site, and it may introduce unnecessary overhead and complexity2.
• B. A full mesh Layer 3 VPN with the BGP route reflector behind the corporate firewall device. A full mesh Layer 3 VPN is a type of VPN that uses MPLS and BGP to provide Layer 3 connectivity and routing between multiple sites over a service provider’s network. Each site has a BGP session with every other site, forming a full mesh topology. A BGP route reflector is a device that reduces the number of BGP sessions required in a full mesh topology by reflecting routes between its clients. A full mesh Layer 3 VPN with the BGP route reflector behind the corporate firewall device is not suitable for connecting two remote sites to your corporate headquarters site, because it does not ensure that traffic passes through the corporate firewall device, and it may require additional configuration and coordination with the service provider3.
• C. A Layer 3 VPN with the corporate firewall acting as the hub device. A Layer 3 VPN is a type of VPN that uses MPLS and BGP to provide Layer 3 connectivity and routing between multiple sites over a service provider’s network. A Layer 3 VPN can have different topologies, such as full mesh, hub-and-spoke, or partial mesh. A Layer 3 VPN with the corporate firewall acting as the hub device is not suitable for connecting two remote sites to your corporate headquarters site, because the corporate firewall may not support MPLS and BGP, and it may require additional configuration and coordination with the service provider3.

References:

• Hub-and-Spoke VPNs Overview
• Full Mesh VPNs Overview
• Layer 3 VPNs Overview

The solution to this problem is to enable address persistence. This will ensure that the same external IP address is used for multiple sessions between an internal host and an external host. This will result in only one authentication being required, as the same external IP address will be used for all sessions.