Comprehensive Detailed Step-by-Step Explanation with All Juniper Security Reference

Understanding the Scenario:

Multinode HA Default Mode Deployment:

In a chassis cluster, two SRX devices operate together to provide high availability.

ICL (Inter-Cluster Link) is Down:

The control and fabric links between the nodes are not operational.

Objective:

Determine how the SRX devices verify each other's activeness without the ICL.

Option A: Custom IP addresses may be configured for the activeness probe.

When the control link is down, SRX devices use an ICMP ping-based activeness probe to check the

peer's status.

Custom IP addresses can be configured as probe targets to verify the peer's activeness.

Reference:

"You can configure the SRX Series device to send activeness probes to a configured IP address to

verify the peer's state when the control link is down."

Source: Juniper Networks Documentation - Control Link Failure Detection

Option D: Each peer sends a probe with the virtual IP address as the source IP address and the

upstream router as the destination IP address.

The SRX devices send ICMP probes to an upstream device using the redundancy group's virtual IP

address as the source.

This helps determine if the peer node is still active by verifying network reachability.

Reference:

"When the control link fails, each node sends ICMP pings to the configured probe addresses using

the redundancy group's virtual IP address as the source."

Source: Juniper Networks Documentation - Chassis Cluster Control Link Failure

Why Options B and C are Incorrect:

Option B: Fabric link heartbeats cannot be used because the ICL (which includes the fabric link) is

down.

Option C: Probes are sent to upstream devices, not using the virtual IP address as the destination.

Conclusion:

The correct options are A and D because they accurately describe how SRX devices verify activeness

without the ICL.

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Comprehensive Detailed Step-by-Step Explanation with All Juniper Security Reference

Understanding Secure Wire:

Secure Wire Feature:

Connects two interfaces directly without any Layer 2 or Layer 3 processing.

No routing or switching lookup occurs.

Use Case:

Ideal for scenarios where traffic needs to pass through the SRX device transparently.

Option B: Secure wire

Secure wire creates a bidirectional link between two interfaces.

Traffic flows between the interfaces as if they are connected by a physical wire.

Reference:

"The secure wire feature allows traffic to pass between two interfaces without any security

processing or route lookups."

Source: Juniper TechLibrary - Secure Wire Overview

Why Other Options Are Incorrect:

Option A: Transparent mode involves Layer 2 switching.

Option C: Mixed mode combines Layer 2 and Layer 3 but doesn't prevent switching/routing lookups.

Option D: Switching mode operates at Layer 2 and includes switching lookups.

Conclusion:

Secure wire is the correct feature to map two interfaces together without switching or routing

lookups.

In this scenario, we need to configure the SRX Series device so that devices in the Local zone (VLAN

10, 10.1.1.0/24 network) can communicate with each other but not with other networks or the SRX

itself. Additionally, you must be able to apply security policies to traffic flows between the devices in

the Local zone.

Explanation of Answer A (Assigning Interface to Security Zone):

You need to assign the interface ge-0/0/1.0 to the Local security zone. This is crucial because the SRX

only applies security policies to interfaces assigned to security zones. Without this, traffic between

devices in the Local zone won't be processed by security policies.

Configuration:

set security zones security-zone Local interfaces ge-0/0/1.0

Explanation of Answer B (Configuring Ethernet-Switching for VLAN 10):

Since we are using Layer 2 switching between devices in VLAN 10, we need to configure the interface

to operate in Ethernet switching mode and assign it to VLAN 10.

Configuration:

set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan-members 10

Explanation of Answer D (Transparent Bridging Mode for Layer 2):

The global mode for Layer 2 switching on the SRX device must be set to transparent-bridge. This

ensures that the SRX operates in Layer 2 mode and can switch traffic between devices without

routing.

Configuration:

set protocols l2-learning global-mode transparent-bridge

Summary:

Interface Assignment: Interface ge-0/0/1.0 is assigned to the Local zone to allow policy enforcement.

Ethernet-Switching: The interface is configured for Layer 2 Ethernet switching in VLAN 10.

Transparent Bridging: The SRX is configured in Layer 2 transparent-bridge mode for switching

between devices.

Juniper Security Reference:

Layer 2 Bridging and Switching Overview: This mode allows the SRX to act as a Layer 2 switch for

forwarding traffic between VLAN members without routing. Reference: Juniper Transparent Bridging

Documentation.

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