Juniper Updated JN0-452 Exam Questions and Answers by nikita

In Juniper Networks Mist AI Wireless, dynamic packet capture (dPCAP) is tightly integrated with events to enable rapid, context-aware troubleshooting. When Mist detects a systemic issue—such as a DHCP server becoming unresponsive—it automatically generates a site-level event because the problem impacts multiple devices within a site rather than a single client.

As shown in the exhibit, the event “DHCP is Unresponsive” lists multiple impacted devices and includes a timeline of contributing network events. This classification is critical: DHCP infrastructure failures are treated as site events, not client-specific or organization-wide events. When such a site event is triggered, Mist can automatically perform a dynamic packet capture on the relevant access points to capture DHCP Discover, Offer, Request, and Acknowledgment (DORA) traffic in real time.

To access this packet capture, an administrator must:

Navigate to the impacted site identified in the event.

Open the corresponding site event (in this case, the DHCP unresponsive event).

Download the automatically generated packet capture file, which can then be opened in Wireshark for detailed protocol-level analysis.

The incorrect options are explained as follows:

Organization events provide high-level visibility and auditing but do not host packet captures.

Client events are used when a single client experiences issues; they are not appropriate when multiple devices are impacted by a shared service failure.

Verifying an impacted client does not expose the dynamic packet capture tied to a site-wide DHCP issue.

Therefore, the correct method is to verify the impacted site and use the corresponding site event to fetch the automatically generated packet capture, making Option B the correct answer.

According to the Mist documentation1, a Mist AP will pull a management IP address from the Native VLAN by default. However, if the Local Status Page is configured for the Site, all the site APs will pull their own IP address from the Management VLAN, but also addresses for each of the VLANs configured on the AP. This is because each AP creates a Switch Virtual Interface (SVI) for each VLAN on its eth0 interface.

The Local Status Page is a feature that allows you to access information about an AP’s status and configuration through a web browser by connecting to its IP address2. This feature can be enabled or disabled at the site level under Site Settings > Access Points > Advanced Settings.

In Juniper Networks Mist AI Wireless, Marvis Minis are purpose-built synthetic clients designed to proactively validate end-user experience by continuously testing the network in the same way a real user device would. To accurately isolate the root cause of connectivity or performance issues, Marvis Minis follow a strict, layered verification sequence that mirrors the logical dependency of network services.

The verification process begins with DHCP. This is the foundational step because, without a valid IP address, no further network communication can occur. Marvis Minis first confirm that the client can successfully complete the DHCP exchange and obtain proper IP configuration, including subnet, gateway, and lease parameters.

Once DHCP is validated, Marvis Minis move to ARP verification. At this stage, the synthetic client confirms it can resolve the MAC address of the default gateway and communicate at Layer 2. ARP issues can prevent traffic from leaving the local network segment even when an IP address is present.

After Layer 2 and Layer 3 reachability are confirmed, Marvis Minis test DNS functionality. DNS resolution is critical for application access, as most modern applications rely on hostname resolution rather than raw IP addresses. Failed or slow DNS responses are a common cause of perceived “application outages.”

Finally, Marvis Minis validate the application layer. This includes testing reachability, response time, and success of specific application transactions such as HTTPS connections, SaaS access, or internal application availability. By the time application testing occurs, all prerequisite network services have already been verified.

The other options are incorrect because they test higher-layer services before validating lower-layer dependencies, which can lead to misleading conclusions. Mist’s ordered approach—DHCP → ARP → DNS → Application—ensures precise fault isolation and actionable insights, allowing Marvis AI to accurately pinpoint where the user experience is breaking down.

In a traditional deployment, a Juniper Mist Access Point is a "cloud-first" device, meaning it expects a constant connection to the Mist Cloud to receive configuration updates and report telemetry. When performing an "AP-on-a-Stick" (APoS) site survey, the AP is often powered by a battery pack and moved to various locations where an active Ethernet backhaul or Internet connection is unavailable.3 To ensure the AP continues to broadcast the required SSIDs for signal measurement in this "disconnected" state, two specific settings must be adjusted within the Mist dashboard.

First, AP Config Persistence must be enabled. By default, Mist APs store their configuration in volatile memory; if an AP reboots (which happens when switching battery packs or moving locations) and cannot reach the Mist Cloud, it may fail to reload its previous configuration. Enabling Config Persistence ensures that the AP writes its current configuration to non-volatile flash memory, allowing it to boot up and start broadcasting the programmed SSIDs even in the absence of a cloud connection.4

Second, AP Uplink Monitoring must be disabled. Mist APs are designed with a safety mechanism where, if the AP loses its gateway connectivity (eth0 link or ping to the gateway), it will stop broadcasting SSIDs to prevent "black-holing" client traffic. In a site survey scenario, the Ethernet port is typically connected only to a battery or a passive PoE injector with no data path.5 If Uplink Monitoring remains active, the AP will detect the lack of a backhaul and disable its radios, making the survey impossible. By disabling this feature, the AP is forced to keep its radios active regardless of the uplink status. Together, these two settings allow the AP to function as a standalone signal source, which is essential for accurate RF environment mapping and pre-deployment validation using Mist AI hardware.