Free ACE-A1.2 Practice Test Questions and Answers (2026) | Cert Empire Practice Questions

The trunk group command associates a VLAN with a specific group of trunk ports. In an MLAG configuration, this feature is used as a best practice to isolate the MLAG peer VLAN. By assigning both the peer-link Port-Channel and the peer VLAN to the same unique trunk group, the switch ensures that the critical MLAG control plane traffic traversing this VLAN is confined exclusively to the peer-link. This prevents the peer VLAN from being inadvertently forwarded ("leaking") onto other trunk ports in the system, which could cause network instability or loops.

A. It groups all the trunks together so that they can traverse the peer-link properly.

This is incorrect. The command associates a VLAN with a group of trunks; it does not group trunks together. Its purpose is traffic isolation, not enabling traversal.

B. It groups the MLAG interfaces together so that they can be reported on both peers.

This is incorrect. The command is applied to a VLAN, not MLAG interfaces (Port-Channels), and its function is unrelated to reporting mechanisms.

D. It ensures that the configured VLAN will be included on all trunks.

This is the opposite of the command's function. It restricts the VLAN to only the trunks assigned to the specific group, rather than ensuring its inclusion on all trunks.

1. Arista Networks EOS 4.27.1F Configuration Guide, Section 22.3.2: MLAG Configuration Example.

The guide states, "The trunk group command ensures that the peer VLAN is only allowed on the peer link and not on any other trunk ports." This directly supports the correct answer by defining the command's purpose as preventing the VLAN from leaking.

2. Arista Networks EOS 4.27.1F Configuration Guide, Section 17.5.2: VLAN Trunk Group Configuration.

This section explains the general mechanism: "VLAN trunk groups provide a mechanism for specifying the set of VLANs that a trunk port can carry... A VLAN associated with a trunk group is carried only by trunk ports that are members of the group." This confirms the restrictive and isolating nature of the command.

3. Arista Design and Best Practices Guide, Section: MLAG Best Practices.

This design guide consistently recommends using a dedicated trunk group for the MLAG peer-link and peer VLAN to ensure control plane traffic is isolated from data plane trunks, reinforcing the principle of preventing traffic leakage.

The VLAN designated for the MLAG peer link is a special-purpose, point-to-point control plane link used exclusively for communication between the two MLAG peer switches. This communication includes synchronizing MAC and ARP tables and exchanging MLAG control protocol messages. The MLAG protocol itself inherently manages the Layer 2 topology to prevent loops from the perspective of downstream devices. Enabling Spanning Tree Protocol (STP) on this dedicated VLAN is not only unnecessary but can be disruptive. If STP were to calculate a loop and block the peer link port, it would sever the control plane connection, leading to a "split-brain" scenario where both peers operate independently, causing network instability and traffic disruption. Therefore, the standard and required best practice is to disable STP on the MLAG peer link VLAN.

The option "False" is incorrect because enabling Spanning Tree on the peer link VLAN directly conflicts with the operational requirements of MLAG. The MLAG control plane relies on a stable, uninterrupted connection over the peer link. STP, by design, could block this link, which would break the MLAG domain and negate the benefits of high availability and redundancy that MLAG is designed to provide.

1. Arista Networks, EOS 4.31.1F Configuration Guide: In the "MLAG" chapter, under the section "Configuring the Peer Link," the guide explicitly states the configuration requirement. It notes, "On the VLAN dedicated to the peer link, spanning tree must be disabled." This is presented as a mandatory step in the configuration process.

Reference: Arista EOS 4.31.1F Configuration Guide, Chapter: "MLAG", Section: "Configuring the Peer Link".

2. Arista Networks, "MLAG Best Practices" Design Guide: This document outlines the recommended design and configuration for a stable MLAG deployment. In the section covering the peer link, it reinforces this rule.

Reference: Arista Design Guides, "MLAG Best Practices", Section: "Peer Link", Subsection: "Configuration". The guide states: "Create a dedicated VLAN for the peer link. This VLAN should not be trunked anywhere else in the network. Disable spanning tree on this VLAN."

3. Arista Networks, "MLAG - Basic Configuration" Article: In this foundational configuration example on the Arista Community Central portal, the steps clearly demonstrate the requirement.

Reference: Arista Community Central, "MLAG - Basic Configuration" (Arista Validated Design), Configuration Example for Peer A and Peer B. Step 3 of the peer link configuration shows the command no spanning-tree vlan being applied to the peer link VLAN.

The command show vxlan address-table is the specific Arista EOS command used to display the VXLAN address table. This table contains the mappings of MAC addresses learned through the VXLAN data plane to their corresponding remote VTEP (VXLAN Tunnel End Point) IP addresses. The output also includes the associated VLAN and VNI (VXLAN Network Identifier), providing a complete view of the Layer 2 reachability information across the VXLAN fabric.

B. show vxlan mac-address-table: This is not a valid Arista EOS command. The correct syntax uses address-table, not mac-address-table, in the VXLAN context.

C. show mac-address-table: This command displays the standard Layer 2 MAC address table. While it will show MACs learned via VXLAN, it lists their port as the logical Vxlan1 interface, not the specific remote VTEP IP address.

D. show vxlan summary: This is not a standard command. Related commands like show vxlan vni summary provide a high-level overview of VNI states, not the detailed MAC-to-VTEP mapping table.

1. Arista Networks EOS Central, VXLAN Routing: The documentation explicitly lists and provides sample output for the show vxlan address-table command, showing its function is to display the "MAC address table for VXLAN." The output clearly contains columns for MAC Address, VLAN, VNI, and Remote VTEP.

Source: Arista EOS Central > Design & Deployment Guides > VXLAN > VXLAN Routing > Verifying VXLAN Routing.

2. Arista Networks EOS 4.21.3F Manual, Section: VXLAN Command Reference: This manual details the show vxlan address-table command. It describes the command as displaying the "VXLAN address table," confirming its purpose is to show MAC addresses learned over VXLAN tunnels and their associated remote VTEPs.

Source: Arista EOS 4.21.3F Manual, Page 1013.

3. Arista Networks, VXLAN Configuration Guide: In the verification sections of various VXLAN configuration examples, show vxlan address-table is consistently used to verify data-plane MAC learning from remote VTEPs. In contrast, show mac-address-table is used to verify local MAC learning and to see that remote MACs are associated with the Vxlan1 interface.

Source: Arista VXLAN Configuration Guide, Section: "Verifying the VXLAN Configuration".

The fundamental purpose of SysDB (System Database) is to serve as the centralized, in-memory state repository for the Arista Extensible Operating System (EOS). In the EOS multi-process architecture, various software agents (e.g., for routing, spanning tree, interface management) operate independently. They publish their state to SysDB and subscribe to relevant state changes from other agents. This state-sharing model decouples the processes from each other, which is key to EOS's high availability and resilience, as individual agents can be restarted without impacting the overall system state or other processes.

B. While user credentials are part of the system state, SysDB's purpose is to store all system state, not just this specific data.

C. Information about discovered systems (e.g., via LLDP) is just one of many types of state stored in SysDB, not its fundamental purpose.

D. SysDB is a core, well-documented, and functional component of the EOS architecture, not a marketing term.

1. Arista Networks, "Arista EOS White Paper": "At the core of EOS is a unique multi-process state-sharing architecture that separates state information from the processes themselves. This is the System Database, or SysDB. All of the switch’s state, from the ASIC forwarding tables to the switch’s spanning tree status, is held in SysDB. Various processes, known as agents, are responsible for a specific function of the switch... These agents interact with SysDB to maintain their state." (Page 3, Section: "EOS Architecture").

2. Arista Networks, "EOS Architecture - EOS Central": "At the core of EOS is a unique multi-process state-sharing architecture that separates state information from the processes themselves. This is the System Database, or SysDB... Each process, or agent, is responsible for a specific function... Agents communicate with each other by publishing and subscribing to changes in SysDB." (Section: "Sysdb").

VXLAN encapsulation adds a series of headers to the original Layer 2 frame to transport it over a Layer 3 network. This added overhead is calculated by summing the sizes of the new headers required for transport across the underlay network. The standard overhead for an IPv4 underlay consists of an Outer Ethernet header (14 bytes), an Outer IP header (20 bytes), an Outer UDP header (8 bytes), and the VXLAN header itself (8 bytes). The total overhead is 14 + 20 + 8 + 8 = 50 bytes. This is a critical consideration for network design, especially regarding MTU settings.

A. 10 bytes: This value is too low and does not account for the multiple headers (L2, L3, L4, and VXLAN) required for encapsulation.

B. 30 bytes: This is an incorrect calculation and does not represent the sum of the standard VXLAN encapsulation headers.

D. 70 bytes: This value represents the overhead when using an IPv6 underlay (40-byte header) instead of IPv4 (14 + 40 + 8 + 8 = 70 bytes). While possible, 50 bytes is the standard for IPv4.

1. Arista Networks, EOS-4.28.0F Manual, "VXLAN Bridging" section, "VXLAN MTU" subsection.

"VXLAN adds 50 bytes of overhead to a packet (14 byte MAC header, 20 byte IPv4 header, 8 byte UDP header, and 8 byte VXLAN header)." This official documentation directly confirms the 50-byte calculation.

2. IETF RFC 7348, "Virtual eXtensible Local Area Network (VXLAN)," Section 5, "VXLAN Packet Format."

This document defines the 8-byte VXLAN header and specifies the encapsulation method: "VXLAN is a Layer 2 overlay scheme over a Layer 3 network. It uses MAC-in-UDP encapsulation..." This supports the inclusion of UDP and underlying IP headers in the overhead calculation.

The statement is false. The zerotouch cancel command in Arista EOS provides a persistent method for disabling Zero Touch Provisioning (ZTP) by creating a specific marker file. When this command is executed, it creates a file named zerotouch-cancelled in the /mnt/flash/ directory. The presence of this file is what the boot process checks for. If this file exists, the ZTP process is skipped on all subsequent reboots, even if a startup-config file is not present. Therefore, issuing the write memory command is not required to make the cancellation of ZTP persistent.

The "True" option is incorrect because the persistence of the ZTP cancellation is not tied to the running-config or startup-config. The zerotouch cancel command performs a direct and persistent file system operation on the switch's flash memory, which survives a reboot independently of any configuration-saving commands like write memory. While saving a valid configuration is the ultimate goal after canceling ZTP, it is not the mechanism that makes the cancellation itself persist.

1. Arista EOS Configuration Guide: In the section describing Zero Touch Provisioning, the guide explains the cancellation process. It states, "To permanently disable ZTP, enter the zerotouch cancel command from the CLI. This command creates the file /mnt/flash/zerotouch-cancelled and ZTP will be disabled on all subsequent reboots." This explicitly confirms that the command itself creates a persistent state via a file, not through a configuration change that needs to be saved.

Source: Arista Networks, EOS 4.27.1F Configuration Guide, Section: "Zero Touch Provisioning (ZTP)", Subsection: "Disabling ZTP".

The command show event-monitor arp is used on an Arista switch to display the historical log of changes to the Address Resolution Protocol (ARP) table. This output is then piped (|) to the grep utility. The grep 10.100.100.6 part of the command acts as a filter, processing the output from the first command and displaying only the lines that contain the IP address "10.100.100.6". Therefore, the command's function is to show all historical ARP table events (additions, deletions, modifications) specifically related to the IP address 10.100.100.6 on the local switch where the command is executed.

A. This is incorrect because the command is executed on the local switch and queries its own event buffer. It does not connect to or retrieve information from a remote switch.

B. This is incorrect as the command filters the event log for entries containing a specific IP address, not for a switch that has a matching ARP address as its own identifier.

D. This is incorrect because Arista's Extensible Operating System (EOS) is built on a Linux kernel, and its command-line interface fully supports standard Linux tools like grep and piping (|) for output filtering.

1. Arista Networks EOS Configuration Guide: In the "Standard CLI Features" section, it details the use of the pipe (|) character to redirect the output of a show command to filters like grep. This confirms that show ... | grep ... is a valid and standard command structure. (Reference: Arista EOS Configuration Guide, section on "CLI Command Basics").

2. Arista Networks EOS Configuration Guide: The "System Monitoring" chapter describes the event-monitor feature. It states, "The show event-monitor command displays the contents of the event monitor buffer." The arp keyword specifies the buffer for ARP events, which logs additions and deletions from the ARP table. (Reference: Arista EOS 4.28.0F Configuration Guide, Chapter 45: System Monitoring, "Event Monitor" section).

3. Arista Networks Command Reference: The show event-monitor command is documented as the primary method for viewing historical event data captured by the event-monitor service. The arp parameter specifically targets the ARP table history. (Reference: Arista Networks Command Reference for the relevant EOS version).

The enable secret command is used to configure a secure, encrypted password for accessing Privilege Exec mode on an Arista switch. This command stores the password as a salted MD5 hash in the running configuration, providing a higher level of security than the enable password command. When a user enters the enable command to escalate privileges, they are prompted for this password. If both enable secret and enable password are configured, the enable secret takes precedence.

A. boot password: This is not a standard command for securing Privilege Exec mode; it relates to the Aboot (bootloader) environment for tasks like password recovery.

C. management secret: This is not a valid Arista EOS command for configuring the Privilege Exec mode password.

D. enable: This is the command used to enter Privilege Exec mode from User Exec mode, not the command used to configure its password.

1. Arista Networks, "EOS System Security Configuration Guide," Release 4.28.0F, Section: "Passwords," Subsection: "Privileged EXEC Mode Password." The document states, "The enable secret command configures the password required to enter privileged EXEC mode... The enable secret command provides more security than the enable password command by storing the password as a salted MD5 hash."

2. Arista Networks, "EOS Configuration Guide," Release 4.21.3F, Section 6.2.1: "Passwords." This section details the use of enable secret to set the password for privileged mode access, explaining its encryption and precedence.

VTEP stands for VXLAN Tunnel Endpoint. It is a functional entity or device that originates and terminates VXLAN tunnels. The VTEP is responsible for the critical functions of encapsulating Layer 2 Ethernet frames from a source virtual network into VXLAN/UDP/IP packets for transport across the underlying Layer 3 network, and decapsulating them at the destination to deliver the original Ethernet frame. This process allows for the extension of Layer 2 segments over a Layer 3 infrastructure, a core capability of VXLAN technology.

B. VNI: VNI stands for VXLAN Network Identifier. It is a 24-bit field in the VXLAN header used to identify a specific virtual network segment, analogous to a VLAN ID, not a device.

C. VXLAN: VXLAN (Virtual Extensible LAN) is the name of the network virtualization protocol itself, which specifies the encapsulation format and behavior, not the device performing the function.

D. VTP: VTP (VLAN Trunking Protocol) is a Cisco-proprietary messaging protocol used to manage the addition, deletion, and renaming of VLANs on a network-wide basis; it is unrelated to VXLAN.

1. IETF RFC 7348, "Virtual eXtensible Local Area Network (VXLAN): A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks":

Section 4.1, "VTEP": "VXLAN Tunnel Endpoint (VTEP). This is the entity that originates and/or terminates VXLAN tunnels." This section explicitly defines the VTEP as the device performing the encapsulation and decapsulation.

Section 5, "VXLAN Header": "VXLAN Network Identifier (VNI): 24 bits. This is an identifier for the virtual network segment." This defines the VNI as a segment identifier, not a device.

2. Arista Networks, "EOS 4.31.2F - 7050X3 Series Configuration Guide":

Chapter 41, "VXLAN", Section "VXLAN Overview": "A VTEP is a device that terminates a VXLAN tunnel, and maps tenant end devices to VXLAN segments. VTEPs perform VXLAN encapsulation and decapsulation." This official vendor documentation directly confirms the role of the VTEP.

The provided output is from the show monitor session MIRROR command. The key lines in the output are Truncate: enabled and Truncate size: 128 bytes. These lines explicitly indicate that the packet truncation feature is active for this port mirroring (SPAN) session. Packet truncation allows for copying only the initial portion of a packet to the destination, which is useful for analyzing headers while conserving bandwidth on the monitoring link and resources on the analysis tool.

B. Advanced Mirroring with ACLs: The output does not show an Access Control List (ACL) being used as a filter for the source traffic. If an ACL were applied, it would be listed in the session details.

C. Agile Ports: Agile Ports refer to the capability of a physical port to operate at different speeds or in breakout modes. This is a physical layer configuration and is not displayed in the show monitor session output.

D. Buffer Tuning: Buffer tuning involves adjusting memory allocation for ingress or egress queues to manage traffic bursts. This is a Quality of Service (QoS) feature, and its status is not shown by the port mirroring command.

1. Arista EOS Configuration Guide 4.27.1F: In the "Port Mirroring (SPAN)" section, under the subsection "Packet Truncation," it states, "Packet truncation enables the switch to forward a specified number of bytes from each packet to the destination port." The guide shows the show monitor session command output, which includes the "Truncate" and "Truncate size" fields, matching the question's image. (See Section 25.3.5 - Packet Truncation).

2. Arista EOS Configuration Guide 4.27.1F: The section on "Mirroring to an ACL" demonstrates that when an ACL is used, the show monitor session output would include a line specifying the ACL name, which is absent in the provided image. (See Section 25.3.4 - Mirroring to an ACL).

The Arista 7500E series is a modular switch platform designed for large-scale cloud and data center environments. It meets all the specified criteria: it is built on a 100% efficient, non-blocking, cell-based fabric architecture. A core feature of its design is Virtual Output Queuing (VOQ) to eliminate head-of-line blocking and ensure lossless performance under congestion. The 7500 platform, which includes the 7500E chassis and compatible line cards (such as the 7500R series), supports line cards that meet and exceed the 3.84 Tbps per-slot capacity requirement, making it the only suitable choice among the options for such a high-performance, large-scale deployment.

A. 7010T: This is a fixed-configuration 1RU switch. It is not a modular chassis and does not have a cell-based fabric or the concept of per-slot capacity.

C. 7300: While the 7300 series is a modular chassis with VOQ, its highest-performing line cards typically offer capacity just below the specified 3.84 Tbps per slot.

D. 7150: This is a fixed-configuration 1RU switch optimized for ultra-low latency. It is not a modular chassis and lacks the specified fabric architecture and scale.

1. Arista 7500E Series Data Sheet: In the "Product Overview," the 7500E is described as a "modular chassis" for "high density data centers." The "Arista EOS" section on page 2 explicitly mentions the "Virtual Output Queue (VOQ) architecture" that "eliminates head-of-line (HOL) blocking."

2. Arista 7500R Series Data Sheet: This document details line cards compatible with the 7500E chassis. The "Product Overview" on page 1 highlights the VOQ architecture. The line card table on page 2 lists modules like the 7500R2-36CQ, which provides 3.6 Tbps of forwarding, demonstrating the platform's ability to meet the high-capacity requirement.

3. Arista 7300X3 and 7320X Series Data Sheet: The line card specifications table on page 2 shows the highest capacity line card, the 7320X-32C, offering "6.4Tbps" of full-duplex throughput, which corresponds to 3.2 Tbps in one direction, falling short of the 3.84 Tbps requirement.

4. Arista Networks, EOS Central - VOQ and Virtual Output Queues: This official documentation explains, "Arista’s 7500, 7300 and 7280R platforms are all VOQ systems... In a VOQ system, there is no head of line blocking." This confirms that both 7500 and 7300 series use VOQ, making the performance per slot the key differentiator in the question.

Arista VMTracer is a feature designed for virtualized data centers that requires the 'V' (Virtualization) license for activation, confirming it is not a free feature. Its functionality allows the switch to communicate with virtualization management systems like VMware vCenter. While VMTracer has broad support across Arista's data center switching platforms and is explicitly supported on vEOS instances, it is not a universal feature across all Arista hardware. For example, it is generally not available on campus-focused switch series. Therefore, its support is limited to certain Arista switches, making both statements A and C correct.

B. VMTracer is not free; it requires the purchase of the Arista 'V' (Virtualization) license to enable its functionality.

D. VMTracer is explicitly supported on vEOS instances, as stated in official Arista configuration guides for use in virtualized environments.

1. Arista Networks, EOS Licensing Philosophy and Guide (2023): The guide details the features included with different EOS software licenses. The 'V' (Virtualization) license section explicitly lists "VM Tracer" as a licensed feature. (Reference: See section on "Virtualization License ('V')").

2. Arista Networks, VM Tracer Configuration Guide, EOS-4.28.0F: This document states, "VM Tracer is supported on all Arista modular and fixed-configuration switches and routers, and on vEOS instances." This confirms support for vEOS (disproving D) and implies the feature is intended for specific classes of devices (routers and modular/fixed switches), not every product. (Reference: "Platform Support" section).

3. Arista Networks, 7050X3 Series Data Sheet: This data sheet for a data center switch lists "VMTracer" under the "Virtualization" software features, confirming its availability on this platform. (Reference: Software Features table).

4. Arista Networks, 720XP Series Data Sheet: This data sheet for a campus access switch does not list VMTracer in its software features, demonstrating that the feature is only supported on "certain" Arista switches and not universally. (Reference: Software Features table).

The Multi-Switch CLI feature in Arista EOS utilizes a concept called "switch-groups" to manage multiple devices from a single point. An administrator can define a named group consisting of several switches. Once a switch-group is created, non-interactive commands (e.g., show commands, configuration changes) can be sent to all switches within that group simultaneously. This capability is central to the Multi-Switch CLI feature, enabling efficient and consistent management across a fleet of devices.

A. groups: This term is too generic. While a "switch-group" is a type of group, the specific feature name within the Multi-Switch CLI context is "switch-groups."

C. chat-rooms: This term is not associated with Arista EOS CLI management. It implies a real-time communication or messaging function, which is unrelated to command execution.

D. chat-groups: Similar to "chat-rooms," this is not a valid Arista EOS feature for managing multiple switches via the CLI.

1. Arista EOS Configuration Guide: In the section detailing Multi-Switch CLI, the guide explicitly states, "Multi-switch CLI allows you to configure and manage multiple switches from a single CLI session. You can create switch groups to send non-interactive commands to multiple switches at once."

Source: Arista EOS 4.27.1F Configuration Guide, Chapter 10: Management Services, Section: "Multi-Switch CLI," Page 225.

2. Arista EOS Central - Multi-Switch CLI: The official documentation on Arista's website describes the feature and its components. It details the creation and usage of switch-group for command distribution.

Source: Arista Networks, EOS Central, "Multi-Switch CLI," section on "Switch Groups." (e.g., https://www.arista.com/en/um-eos/eos-multi-switch-cli) The documentation outlines the command syntax switch-group for creating these entities.

The Extensible Messaging and Presence Protocol (XMPP) management interface on Arista EOS is disabled by default. This is consistent with security best practices for network devices, which advocate for a minimal attack surface upon initial deployment. An administrator must explicitly enter the management xmpp configuration mode, define the required connection parameters (such as server, Jabber ID, and password), and then explicitly enable the service using the no shutdown command within that configuration context.

The statement "True" is incorrect. Enabling a management protocol like XMPP by default would expose the device to unnecessary security risks without explicit configuration and intent from a network administrator. Arista EOS follows a secure-by-default principle where non-essential management services must be deliberately enabled.

1. Arista EOS Configuration Guide: In the section detailing the configuration of management interfaces, the guide explicitly states that the XMPP feature is not active by default. The configuration process requires entering a specific configuration mode and enabling the service.

Source: Arista EOS 4.28.0F Configuration Guide

Reference: Chapter 61: XMPP, Section 61.2 "Configuring XMPP". The section begins with the steps to enter the management xmpp configuration mode, which implies the feature is not pre-configured or active. The inclusion of the no shutdown command in the configuration example further confirms that the service is administratively disabled by default.

2. Arista Design and Deployment Guides: Security and management best practice documents emphasize enabling only necessary services.

Source: Arista Design Guide - Switch Hardening

Reference: Section "Control Plane Hardening". This section typically advises disabling all unused management interfaces and protocols to reduce the device's attack surface. The default state of XMPP being disabled aligns directly with this fundamental security principle.

Arista's Latency Analyzer (LANZ) is a feature designed to detect and report microbursts and network congestion by monitoring queue lengths. When a queue's length surpasses a configured high threshold, LANZ generates a "Start" record, signaling the beginning of a congestion event. While the queue remains congested (above the high threshold), periodic "Update" records are sent, providing details on the ongoing event, such as the maximum queue length observed. Once the queue length drops below a configured low threshold, an "End" record is generated, marking the conclusion of the congestion event. These three record types—Start, Update, and End—provide a complete lifecycle view of each congestion incident.

A. The term "Stop" is incorrect. LANZ uses "End" to signify that the queue length has fallen below the low threshold and the congestion event has concluded.

C. The term "Begin" is incorrect. The official terminology used by Arista LANZ for initiating a congestion record is "Start".

D. Both "Begin" and "Stop" are incorrect terms. The correct terminology used in LANZ event reporting is "Start" and "End" respectively.

1. Arista Networks. (2021). EOS 4.25.1F Configuration Guide. Section 41.2.1, "LANZ Operation", Page 911. "When a queue length exceeds its configured high threshold, LANZ generates a congestion start record... While the queue length remains above the high threshold, LANZ generates congestion update records... When the queue length drops below the configured low threshold, LANZ generates a congestion end record."

2. Arista Networks. (2013). Arista Latency Analyzer (LANZ) White Paper. Page 3, "How LANZ Works". "When a queue length exceeds its configured high threshold, LANZ generates a congestion start record... While the queue length remains above the high threshold, LANZ generates congestion update records... When the queue length drops below the configured low threshold, LANZ generates a congestion end record."

According to Arista EOS documentation, when a scheduled job is created, the system automatically generates a directory to store the output of the commands executed by that job. This directory is created inside the /mnt/flash/schedule/ path. The name of this output directory precisely matches the name assigned to the job during its configuration. EOS job names are case-sensitive, so a job created with the name "Colleen-Job" will have its output stored in a directory named "Colleen-Job", preserving the capitalization.

A. This is incorrect because EOS preserves the case of the job name for the directory. It does not convert the name to lowercase.

B. This path is incorrect as it omits the required /schedule/ parent directory where all scheduled job outputs are placed by default.

C. This is an alias for /mnt/flash/Colleen-Job and is incorrect because it also omits the mandatory /schedule/ parent directory.

1. Arista EOS Configuration Guide: In the "Scheduled Jobs" section, it is stated: "The job name is case-sensitive. When a schedule is created, the switch creates a directory named for the job in /mnt/flash/schedule. The output of the commands in the job is placed in this directory." (Reference: Arista EOS 4.27.2F Configuration Guide, Chapter 48: System Management, Section: Scheduled Jobs).

Zero Touch Provisioning (ZTP) is a foundational feature of the Arista Extensible Operating System (EOS), not a feature exclusive to a specific hardware series. All Arista switches running EOS, including the 7050, 7280E, 7300, and 7500E series, ship from the factory with ZTP enabled by default. This core functionality allows any of these devices to automatically discover a provisioning server, download a boot script, update its EOS image, and apply a device-specific configuration file upon initial power-on. This process eliminates the need for manual console-based configuration for any Arista switch. Therefore, all the listed options are correct.

No options are incorrect. ZTP is a universal feature across all Arista switch platforms running EOS, making all listed series valid answers.

1. Arista Networks, EOS 4.31.1F Configuration Guide: In the "Zero Touch Provisioning" chapter, the overview states, "Zero Touch Provisioning (ZTP) is a process that configures Arista switches automatically without user intervention." The guide does not specify any hardware limitations, indicating its universal applicability across EOS devices.

2. Arista Networks, Design and Implementation Guides, "Zero Touch Provisioning (ZTP)": This official design guide explicitly states in its introduction, "All Arista switches running EOS ship from the factory in ZTP mode." This confirms the feature is present on all platforms, not just a select few.

3. Arista Networks, "Arista 7050X3 Series Datasheet": Under the "Extensible Operating System" section, "Zero Touch Provisioning (ZTP)" is listed as a key feature for provisioning and configuration, confirming its support on the 7050 series. Similar statements are found in the datasheets for the 7280, 7300, and 7500 series switches.

The correct command to specify the boot image for the next reload on an Arista switch is boot system. This command requires the full path to the software image file. The path must include the filesystem where the image is stored (typically flash:), a colon and a forward slash (:/), followed by the exact filename of the EOS image (.swi file). Option C provides the complete and syntactically correct command to set the boot image to EOS-4.15.1F.swi located in the flash memory.

A. This option specifies an incorrect filename (EOS-4.15.1.swi), which is missing the "F" from the version 4.15.1F stated in the question.

B. This command is incomplete as it omits the mandatory filesystem path (flash:/), preventing the switch from locating the specified image file.

D. This command uses incorrect syntax. A space is used between the filesystem (flash) and the filename, whereas the correct syntax requires :/.

1. Arista Networks, EOS User Manual, Release 4.23.0F: In the "Command-Line Interface" section, under "Configuration Commands," the boot system command is detailed. The syntax is shown as boot system flash:/.swi. This confirms the requirement for the flash:/ prefix and the full image name. (Reference: Arista EOS User Manual, specific examples in software upgrade sections).

2. Arista Networks, EOS 4.21.1F System Management Configuration Guide: In the chapter on "Managing System Files," the section "Specifying the Boot Image" explicitly documents the command. An example provided is switch(config)# boot system flash:/EOS-4.21.1F.swi, which directly validates the format used in the correct answer. (Reference: Document ID: EOS-4.21.1F-SysMgmt, Page 15, "Specifying the Boot Image").

When one of two MLAG peer switches is reloaded, all its physical links go down, including the member links of any Port-Channels connected to dual-homed hosts. The remaining active MLAG peer detects the failure via the peer-link heartbeat and continues to forward traffic. The dual-homed host, using LACP, detects the link failure to the rebooting switch and redirects all traffic to the remaining active link connected to the healthy peer. While this prevents a complete network outage for the host, its total available bandwidth through the MLAG domain is halved until the rebooting switch comes back online and its MLAG ports are restored.

B. The peer switch also reboots to ensure network stability.

This is incorrect as it would defeat the primary purpose of MLAG, which is to provide high availability and redundancy by surviving a single switch failure.

C. The peer switch sends out gratuitous BPDUs to let the network know that it has assumed the root-bridge role.

This is a possible secondary effect related to Spanning Tree Protocol (STP) if the rebooting switch was the root, but it is not the most direct or guaranteed result. The primary impact is on the data path capacity.

D. Nothing bad ever happens when MLAG is enabled!

This is incorrect. While MLAG provides resilience against complete outages, the temporary loss of 50% of the available bandwidth is a significant, albeit managed, negative event.

1. Arista Networks, EOS Configuration Guide, Release 4.28.0F: In the "MLAG Concepts" section, under "Failure Scenarios," the documentation describes the behavior during a peer switch failure. It states, "If an MLAG peer fails, the remaining peer continues to forward traffic. From the perspective of the attached device, one of the links in its LAG went down, and it continues to forward traffic on the remaining link(s)." This directly supports the loss of a link and the continuation of traffic on the other, which implies a reduction in capacity.

2. Arista Networks, MLAG - High Availability: This design guide explains the fundamental principle of MLAG. In the section on "MLAG Failure Scenarios," it details that upon the failure of one peer, "traffic from the access device is forwarded to the remaining active MLAG peer." This confirms that connectivity is maintained but through fewer links, hence reduced capacity. (Reference: Arista.com Design and Deployment Guides).

3. Arista Networks, EOS Central (Legacy Documentation Archive), MLAG Basic Configuration: Older configuration guides for versions similar to 4.14 consistently describe MLAG's role in providing hitless forwarding during the failure or upgrade of a single peer. The core mechanism relies on the remaining switch handling all traffic, which inherently means the paths to the failed switch are unavailable. (Reference: Arista EOS Central archives for MLAG).

In Arista's Extensible Operating System (EOS), extensions must be explicitly configured to load automatically upon system boot. The command copy installed-extensions boot-extensions achieves this by taking the list of all currently installed extensions (represented by the keyword installed-extensions) and writing this list to a special configuration file named boot-extensions. During the boot sequence, EOS reads the boot-extensions file and loads each extension listed within it, ensuring their persistence across reboots.

A. install extensions permanent

This is not a valid EOS command. The install extension command does not have a permanent keyword; persistence is managed separately.

B. boot installed-extensions

This is not a valid EOS command. The boot command is used to configure the system's primary boot image (boot system ...), not for managing extensions.

C. copy extensions: boot-extensions:

This command is syntactically incorrect. extensions: refers to the directory, not the list of installed extensions. The correct keyword is installed-extensions (without a colon).

1. Arista EOS Configuration Guide (Version 4.31.1F): In the "Extensions" section, under the subsection "Making an Extension Persistent," the guide explicitly states: "To make all currently installed extensions persistent, copy the list of installed extensions to the boot-extensions file." It then provides the exact command: switch#copy installed-extensions boot-extensions. (Section 11.10.3)

2. Arista Networks Documentation - Managing EOS Extensions: This official article details the lifecycle of extensions. In the section "Making an Extension Persistent," it states: "To ensure that all currently installed extensions are loaded on the next reboot, copy the list of installed extensions to the boot-extensions file: copy installed-extensions boot-extensions". (Arista EOS Central, Document ID: TOI-122)