Free Cisco 300-710 Practice Exam with Questions & Answers | Set: 9

To configure an isolated bridge group for Integrated Routing and Bridging (IRB) mode on a Cisco Secure Firewall device, the action to take is to leave the BVI (Bridge Virtual Interface) interface name empty. This ensures that the bridge group operates in an isolated manner, where Layer 3 routing is not applied to the bridged interfaces, effectively isolating the traffic within the bridge group.

Steps:

Access the firewall's configuration interface.

Configure the bridge group interfaces.

Ensure that the BVI interface name is left empty to isolate the bridge group.

This configuration prevents Layer 3 routing for the isolated bridge group, ensuring that traffic remains contained within the bridge group.

The Capture w/Trace wizard in Cisco FMC allows you to capture packets on an FTD device and trace their path through the Snort engine. This can help you troubleshoot connectivity issues from an endpoint behind an FTD device and a public DNS server, as well as verify the Snort verdict for the DNS traffic. The Capture w/Trace wizard lets you specify the source and destination IP addresses, ports, and protocols for the packets you want to capture and trace, as well as the FTD device and interface where you want to perform the capture. You can also apply filters to limit the capture size and duration. After you start the capture, you can ping the DNS server from the endpoint and then view the captured packets and their Snort verdicts in the FMC web interface2.

To use the Capture w/Trace wizard in Cisco FMC, you need to follow these steps2:

In the FMC web interface, navigate to Troubleshooting > Capture/Trace.

Click New Capture.

Choose an FTD device from the Device drop-down list.

Choose an interface from the Interface drop-down list.

Enter the source and destination IP addresses, ports, and protocols for the packets you want to capture and trace. For example, if you want to capture DNS queries from an endpoint with IP address 10.1.1.100 to a DNS server with IP address 8.8.8.8, you can enter these values:

Source IP: 10.1.1.100

Source Port: any

Destination IP: 8.8.8.8

Destination Port: 53

Protocol: UDP

Optionally, apply filters to limit the capture size and duration. For example, you can set the maximum number of packets to capture, the maximum capture file size, or the maximum capture time.

Click Start.

Ping the DNS server from the endpoint and wait for some packets to be captured.

Click Stop to stop the capture.

Click View Capture to see the captured packets and their Snort verdicts.

The other options are incorrect because:

Performing a Snort engine capture using tcpdump from the FTD CLI will not allow you to trace the path of the packets through the Snort engine or verify their Snort verdicts. Tcpdump is a command-line tool that can capture packets on an FTD device, but it does not provide any information about how Snort processes those packets or what actions Snort takes on them2.

Creating a Custom Workflow in Cisco FMC will not help you troubleshoot a connectivity issue from an endpoint behind an FTD device and a public DNS server. A Custom Workflow is a user-defined set of pages that display event data in different formats, such as tables, charts, maps, and so on. A Custom Workflow does not allow you to capture or trace packets on an FTD device3.

Running the system support firewall-engine-debug command from the FTD CLI will not allow you to simulate real DNS traffic on the FTD device or verify the Snort verdict for that traffic. The firewall-engine-debug command is a diagnostic tool that can generate synthetic packets and send them through the Snort engine on an FTD device. The synthetic packets are not real network traffic and do not affect any connections or policies on the FTD device4.

To filter traffic between multiple subnets, the engineer must implement the firewall in routed mode. In routed mode, the firewall operates as a Layer 3 device, capable of routing traffic between different IP subnets. This mode is appropriate for filtering traffic between LAN, DMZ, and WAN subnets.

Steps to configure routed mode:

Access the firewall's management interface.

Configure interfaces for each subnet (LAN, DMZ, WAN) with appropriate IP addresses and network masks.

Define security zones and apply access control policies to filter traffic as required.

This ensures that the firewall can inspect and route traffic between the different subnets, providing the necessary security and control.

Traditionally, a firewall is a routed hop and acts as a default gateway for hosts that connect to one of its screened subnets. A transparent firewall, on the other hand, is a Layer 2 firewall that acts like a “bump in the wire,” or a “stealth firewall,” and is not seen as a router hop to connected devices. However, like any other firewall, access control between interfaces is controlled, and all of the usual firewall checks are in place. Layer 2 connectivity is achieved by using a "bridge group" where you group together the inside and outside interfaces for a network, and the ASA uses bridging techniques to pass traffic between the interfaces. Each bridge group includes a Bridge Virtual Interface (BVI) to which you assign an IP address on the network. You can have multiple bridge groups for multiple networks. In transparent mode, these bridge groups cannot communicate with each other.https://www.cisco.com/c/en/u s/td/docs/security/asa/asa97/configuration/general/asa-97-general-config/intro-fw.html