JN0-637 Dumps With Exact Questions and Answers

Persistent NAT with target host allows external hosts to establish connections only when the internal device initiates a session first, ideal for specific interactive applications. Refer to Juniper Persistent NAT Documentation.

The scenario requires that external hosts be able to initiate a connectiononly if the internal device has already initiated a connection. The correct solution isPersistent NAT with target host, which ensures that a specific external host can initiate new connections back to the internal device, but only after the internal device has established a session first.

Persistent NAT with Target Host (Answer C): This allows the internal device to initiate a connection, and once established, the specified external host can also initiate new connections to the internal device on the same NAT mapping.

Example Configuration:

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set security nat source persistent-nat permit target-host-port

This solution is appropriate when controlled bidirectional communication is required based on an internal-initiated connection.

Aggressive mode is required when an IP address is dynamically assigned, such as through DHCP, as it allows for faster establishment with less identity verification. More details are available in Juniper IKE and IPsec Configuration Guide.

The configuration shown in the exhibit highlights that theRemoteSite1SRX Series device is using DHCP to obtain an IP address for its external interface (ge-0/0/2). This introduces a challenge in IPsec VPN configurations when the public IP address of the remote site is not static, as is the case here.

Aggressive modein IKE (Internet Key Exchange) is designed for situations where one or both peers have dynamically assigned IP addresses. In this scenario,aggressive modeallows the devices to exchange identifying information, such as hostnames, rather than relying on static IP addresses, which is necessary when the remote peer (RemoteSite1) has a dynamic IP from DHCP.

Correct Action (D): Changing the IKE policy mode toaggressivewill resolve the issue by allowing the two devices to establish the VPN even though one of them is using DHCP. In aggressive mode, the initiator can present its identity (hostname) during the initial handshake, enabling the VPN to be established successfully.

Incorrect Options:

Option A: Changing the external interface to st0.0 is incorrect because the st0 interface is used for the tunnel interface, not for the IKE negotiation.

Option B: Changing to IKE version 2 would not resolve the dynamic IP issue directly, and IKEv1 works in this scenario.

Option C: Changing the IKE proposal set to basic doesn't address the dynamic IP challenge in this scenario.

Juniper References:

Juniper IKE and VPN Documentation: Provides details on when to use aggressive mode, especially when a dynamic IP address is involved.

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In mixed mode, SRX devices can simultaneously handle Layer 2 switching and Layer 3 routing, but a reboot is required when configuring Layer 2 and Layer 3 interfaces to ensure the configuration takes effect. Layer 2 packets are switched within the defined bridge domain. Further guidance on SRX mixed mode can be found at Juniper Mixed Mode Documentation.

When an SRX Series device is configured inmixed mode, both Layer 2 switching and Layer 3 routing functionalities can be used on the same device. This enables the SRX to act as both a router and a switch for different interfaces. However, there are certain considerations:

Explanation of Answer C (Reboot Requirement):

After configuring the SRX to operate with at least one Layer 2 interface and one Layer 3 interface, the device needs to be rebooted. This is required to properly initialize the mixed mode configuration, as the SRX needs to switch between Layer 2 and Layer 3 processing modes.

Explanation of Answer D (Layer 2 Traffic Handling):

In mixed mode, traffic from Layer 2 interfaces is switched within the samebridge domain. A bridge domain defines a Layer 2 broadcast domain, and packets from Layer 2 interfaces are forwarded based on MAC addresses within that domain.

Juniper Security Reference:

Mixed Mode Overview: Juniper SRX devices can operate in mixed mode to handle both Layer 2 and Layer 3 traffic simultaneously. Reference: Juniper Mixed Mode Documentation.

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