Juniper JN0-637 - Security, Professional (JNCIP-SEC)

The exhibit describes a Chassis Cluster configuration with high availability (HA) settings. The key information is related to Service Redundancy Group 1 (SRG1) and its failover behavior between the two peers.

Explanation of Answer D (Packet Forwarding after Failover):

In a typical SRX HA setup with active/backup configuration, if the SRG1 group moves to peer 2 (the backup), peer 1 (previously the active node) will forward packets to peer 2 instead of dropping them. This ensures smooth failover and seamless continuation of services without packet loss.

This behavior is part of the active/backup failover process in SRX chassis clusters, where the standby peer takes over traffic processing without disruption.

Juniper Security Reference:

Chassis Cluster Failover Behavior: When a service redundancy group fails over to the backup peer, the previously active peer forwards traffic to the new active node. Reference: Juniper Chassis Cluster Documentation.

==========

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

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.

Explanation:

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.

DNS doctoring modifies DNS responses for hosts behind NAT devices, allowing them to receive the correct public IP address for internal resources when queried from the public network. This prevents issues where private IPs are returned and are not reachable externally. For details, visit Juniper DNS Doctoring Documentation.

In this scenario, Host A is trying to resolve the domain name web.acme.com, but the DNS resolution returns the private IP address of the web server instead of its public IP. This is a common issue in networks where private addresses are used internally, but public addresses are required for external clients.

Explanation of Answer C (DNS Doctoring):

DNS doctoring is a feature that modifies DNS replies as they pass through the SRX device. In this case, DNS doctoring can be used to replace the private IP address returned in the DNS response with the correct public IP address for Host A. This allows external clients to reach internal resources without being aware of their private IP addresses.

Configuration Example:

bash

set security nat dns-doctoring from-zone untrust to-zone trust

Juniper Security Reference:

DNS Doctoring Overview: DNS doctoring is used to modify DNS responses so that external clients can access internal resources using public IP addresses. Reference: Juniper DNS Doctoring Documentation.

==========

==========

==========

==========

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

Understanding the Session Output:

Session State: Valid

Indicates that the session is active and permitted by security policies.

Policy Name: L1-to-L9/11

Shows the policy that allowed the session.

In Direction:

Source: 10.10.101.10

Destination: 10.10.102.10

Packets: 1

Bytes: 84

Out Direction:

Packets: 0

Bytes: 0

Indicates no return traffic.

Option A: The traffic is permitted.

Explanation:

The session state is Valid, and a policy name is specified.

This means the SRX device allowed the traffic.