VNX301 Practice Questions

The symptoms described—DNS resolution succeeding while application traffic fails—strongly point to a Network Address Translation (NAT) or firewall policy issue. In a Versa SD-WAN Direct Internet Access (DIA) scenario, Carrier-Grade NAT (CGNAT) is commonly used to translate private branch IP addresses to a public IP for internet access. If the CGNAT rule is misconfigured or not matching the application traffic, DNS queries (UDP/53) might work, but subsequent TCP/HTTP/HTTPS connections will fail. Checking the CGNAT and associated DNS forwarding rules is the logical first step.

B. OSPF area ID and BGP MED: These are routing protocol attributes that are irrelevant to a basic DIA failure where initial DNS lookup already works.

C. SNMP community and syslog server: These are configurations for network monitoring and logging; they do not impact the forwarding of user application traffic.

D. VRRP priority and DHCP lease time: These relate to gateway redundancy and IP address assignment, which are unlikely causes if DNS resolution is already successful.

1. Versa Networks, "Versa Secure SD-WAN Configuration Guide," Release 21.2.2, Section: "Configuring DIA Using a Centralized Internet Gateway," pp. 345-350. This section details the necessary components for DIA, including NAT pools and rules which are fundamental for application traffic to exit to the internet.

2. Versa Networks, "CGNAT Configuration Guide," Release 22.1.0, Section: "Troubleshooting CGNAT," p. 28. This guide outlines common issues where misconfigured NAT rules can block specific types of traffic while allowing others, consistent with the scenario.

The show vsm p2mp tunnel-remote-endpoint command is executed on the Versa Controller to display the remote site information learned for SD-WAN overlay tunnels. This command's output shows the remote endpoint's IP address, the site ID, and the source from which this information was learned (e.g., BGP or static configuration). This directly addresses the need to verify if the Controller has successfully learned the necessary remote endpoint objects required for a branch to establish its overlay tunnels. Without this information on the Controller, the branch will not receive the required control plane messages to build tunnels to other sites.

B. show interfaces brief: This command displays the status of local physical and logical interfaces on a device, not the SD-WAN control plane state for remote sites.

C. show system storage: This command shows disk partition usage and storage information, which is unrelated to SD-WAN tunnel formation or control plane learning.

D. show orgs org-services cgnat summary: This command is used for troubleshooting Carrier-Grade NAT services and has no relevance to learning SD-WAN remote endpoints.

Versa Networks, "VOS™ CLI Reference Guide, Release 21.2.2", Page 1188. The guide details the show vsm p2mp tunnel-remote-endpoint command, specifying its use for displaying P2MP tunnel remote endpoint information learned by the VSM daemon.

The primary distinction between a stateful firewall and a Next-Generation Firewall (NGFW) within the Versa solution lies in the depth of inspection and licensing. A stateful firewall operates at Layers 2-4, tracking connection states based on IP addresses and ports. An NGFW incorporates all stateful capabilities but adds Layer 7 application awareness, user identity integration, and advanced threat prevention. This advanced functionality is typically enabled through a specific, higher-tier software license, whereas basic stateful firewalling is often included in standard licenses.

B. NGFW functionality is enabled by licensing on the standard Versa Operating System (VOS), not by requiring a completely different VOS image.

C. Both stateful and NGFW security policies generate logs that are sent to Versa Analytics for monitoring and reporting; this is a fundamental feature of the platform.

1. Versa Networks, "VOS™ Next Generation Firewall Configuration Guide, Release 22.1," Document ID: VOS-NGFW-CG-22.1, Chapter 1: "Introduction to Versa NGFW," p. 8. (This chapter differentiates L4 stateful inspection from L7 application-aware inspection).

2. Versa Networks, "Versa Networks Solution Licensing and Ordering Guide," Document ID: V-LIC-2023-Q2, Section 2: "Software Subscription Tiers," p. 4. (This document outlines which features, such as Stateful Firewall vs. NGFW/UTM, are included in different license packages).

Versa SD-WAN licensing is subscription-based. A new CPE automatically on-boards (ZTP) to Versa Director, where the Director pulls the purchased license entitlements from Versa’s license server and assigns them to the device; licensing is always managed from Director, not directly on the Controller or via pre-loaded hardware keys.

A. Versa issues entitlement tokens, not soft licenses that the customer installs manually per device.

B. Hardware appliances are sold separately; buying licenses alone does not include pre-licensed CPEs.

D. Controllers forward control-plane traffic but do not perform license assignment; only Director has that role.

1. Versa Licensing and Subscription Guide v21.1, “Director-based license management,” p. 6–8.

2. Versa Secure SD-WAN ZTP Guide 20.2, “License retrieval during ZTP,” p. 14.

Protocols like SCP and FTP typically use a single, long-lived TCP session for the data transfer portion of a file transfer. To simulate this accurately, a performance test must also use a single session. The VOS CLI tools network-diagnostics speed-test command includes a single-session option specifically for this purpose. This method provides a more realistic measurement of single-stream throughput, which can differ significantly from the multi-stream tests used to measure maximum link capacity.

A. The default internet speed test from Versa Director uses multiple parallel sessions to find the maximum aggregate throughput, not to simulate a single file transfer.

C. The show interfaces brief command provides cumulative packet and byte counters, not a real-time performance test that simulates a specific application's behavior.

D. The SD-WAN SLA monitor measures link quality (latency, jitter, loss) using small probe packets, not the bulk data throughput characteristic of a file transfer.

1. Versa Networks, "Versa Operating System (VOS) CLI Reference Guide," Release 21.2.2, Document ID: VOS-21.2.2-CLI-REF, Section: "tools network-diagnostics speed-test," pp. 1205-1207. (Documents the single-session parameter and its purpose for testing).

2. Versa Networks, "Versa Secure SD-WAN Configuration and Administration Guide," Release 21.2.2, Document ID: VOS-21.2.2-SD-WAN-C-A, Section: "Monitoring > Speed Test," p. 812. (Describes the speed test functionality and distinguishes between multi-session and single-session tests).

In the Versa onboarding process, the "first branch-connect" notification in Versa Director signifies the successful completion of ZTP Stage 1, where the branch CPE has connected to the staging server. The subsequent "staged branch-connect" notification indicates the successful completion of Stage 2, where the CPE has established a control connection to the Versa Controller. The absence of this second notification strongly implies a failure during Stage 2. This stage is critically dependent on IP connectivity and successful IPsec tunnel establishment between the branch and the Controller. Therefore, investigating this data path is the logical first step.

A. Versa Analytics disk usage relates to log storage and would not prevent the initial control plane connection between a branch and a Controller.

C. LDAP authentication is used for administrative user access to Versa Director, not for the device's automated onboarding process.

D. The URL filtering database is a security feature downloaded after the device is fully onboarded and operational; it is not a factor in initial connectivity.

Versa Networks, "VOS™ Zero Touch Provisioning Deployment Guide," Version 22.2.1, Chapter: Troubleshooting ZTP, Section: Stage 2 Failures, p. 45. (This section identifies connectivity issues between the branch and Controller as the primary cause of Stage 2 failures.)

Versa Networks, "Versa Secure SD-WAN Troubleshooting Guide," Version 21.2.3, Section: Onboarding and Provisioning Issues, Subsection: Device Stuck After Staging Server Connection. (This document outlines troubleshooting steps that prioritize checking firewall rules, routing, and IPsec logs for the branch-to-Controller path.)

The key symptoms are "increasing out-of-ports errors" while "out-of-address errors remain zero." This indicates that the CGNAT pool has available public IP addresses but has exhausted the available TCP/UDP port numbers for a given IP address. Each new session requires a unique source port for translation. When all 64,511 usable ports for an IP are allocated, new sessions are dropped, resulting in "out-of-ports" errors. The intermittent nature of the failures is consistent with the pool reaching its port limit during peak usage.

B. If the NAT pool had no IP addresses, the "out-of-address" error counter would be increasing, which contradicts the scenario.

C. A rule matching the wrong zone is a policy misconfiguration that would likely cause consistent failures, not intermittent ones tied to port exhaustion counters.

D. OSPF is a LAN-side routing protocol and is unrelated to the DIA/CGNAT function, which handles address and port translation for internet-bound traffic.

1. Versa Networks, "Versa Operating System (VOS) CGNAT Configuration Guide," Release 21.2.2, Document ID: VOS-21.2.2-CGNAT-C-G, Section: "Monitoring and Troubleshooting CGNAT," pp. 55-57. (Explains the meaning of out-of-ports and out-of-address errors).

2. Versa Networks, "Versa Operating System (VOS) CLI Reference Guide," Release 21.2.2, Document ID: VOS-21.2.2-CLI-REF, Section: "show cgnat pool counters," pp. 345-346. (Details the CLI command and its output fields, including the error counters).

The branch onboarding process transitions from a temporary staging connection to a permanent control connection with the designated Controller. The stage-two configuration, pushed by Director, contains the necessary parameters for this transition. The most critical parameter is the IP address of the Controller, which is configured as the remote endpoint in the branch's IPsec (or TLS) profile. If this IP address is missing, incorrect, or unreachable, the branch device cannot establish the secure tunnel to the Controller and will fall back to its last known connection, the staging server.

A. Analytics log collector IP address: A missing analytics collector IP would prevent monitoring data from being sent but would not stop the primary control connection.

C. Tenant LAN DHCP pool: This configuration is for the local area network and has no impact on the device's ability to connect to the WAN-side Controller.

D. URL filtering profile: This is a security policy feature that is applied after the control connection is established; it is not a prerequisite for it.

1. Versa Networks, "Zero Touch Provisioning Quick Start Guide, Release 21.2.2", Section: "Onboarding Workflow", Page 10. The guide explains that the stage-2 configuration "contains the information for the CPE to connect to the controller," highlighting the Controller IP as the essential element for the next step.

2. Versa Networks, "VOS Configuration Guide, Release 21.2.2", Section: "Configuring IPsec Tunnels". This section details the requirement of a remote IP address in the IKE gateway configuration for the tunnel to be established, which is the mechanism used for the control connection.

The show system package-info command is the standard Versa Operating System (VOS) command to display detailed information about the installed software packages. The output includes the currently active (running) software version, the version stored in the alternate partition, and the factory base version. This is the precise command needed to determine the running VOS image before an upgrade.

show system uptime displays how long the device has been operational, not the software version.

show interfaces brief provides a summary of the status of network interfaces, not software information.

show class-of-services interfaces brief displays Class of Service statistics for interfaces, which is unrelated to the installed OS image.

1. Versa Networks, VOS™ CLI Reference Guide, Release 21.2.2, "show system package-info" command description, Section: System Commands. The guide explicitly states this command is used to view information about the software packages on the system.

2. Versa Networks, Versa Secure SD-WAN Software Upgrade Guide, Release 22.1, Chapter: "Upgrading the Software", Section: "Verifying the Current Software Version". This guide instructs administrators to use show system package-info as a preliminary step before initiating a software upgrade.

In Versa Director, the monitoring dashboards for branch sites do not display real-time data by default to conserve resources. To view live statistics such as bandwidth utilization for WAN circuits, the administrator must explicitly enable this feature. The exhibit shows the "Live Data" checkboxes for both the MPLS and INET circuits are unchecked. Selecting the "Live Data" checkbox for all relevant WAN circuits will initiate a live data stream from the branch appliance to Versa Director, which then populates the corresponding graphs with current information.

A. Refreshing the page only reloads the dashboard's static elements; it does not activate the live data feed required to populate the graphs.

C. Selecting "Live Data" for only the MPLS circuit would not populate the graph for the INET circuit, failing to meet the requirement for all circuits.

D. Toggling the setting for a single circuit will not enable monitoring for the other circuits that are also not displaying data.

Versa Networks, "Versa Director Administrator Guide," Version 22.2.1, Chapter: Monitor, Section: Monitoring Branch Appliance Details, pp. 215-217. (This section describes the monitoring dashboard interface, including the use of "Live Data" toggles to view real-time statistics.)

Versa Networks, "VOS™ Configuration Guide," Version 22.2.1, Part 3: Monitoring and Troubleshooting, Section: Monitoring from Versa Director. (This section details the procedures for viewing live and historical data, emphasizing that live views must be actively enabled.)