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Arista ACE-S Automation (Foundations) study materials
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Arista ACE-S Automation (Foundations) practice questions

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Question 1Arista EOS and CloudVision Fundamentals

Which Arista technology uses a standards-based approach for network-wide state with an in-band, per-node control plane that keeps forwarding decisions local to each switch?

  1. Arista CloudEOS
  2. Arista EOS-VM
  3. Arista Extensible Operating System (EOS) Correct answer.
  4. Arista CloudVision

Explanation

EOS is Arista's single-image network operating system that runs a consistent control plane across all platforms while keeping forwarding state local to each device. Its architecture emphasizes modular processes and in-service upgrades. CloudVision is a management and telemetry platform, not the per-node OS.

Question 2Arista EOS and CloudVision Fundamentals

In EOS, which command-line mode is entered immediately after logging in and allows only basic show commands and mode transitions?

  1. Privileged EXEC mode
  2. Interface configuration mode
  3. User EXEC mode Correct answer.
  4. Global configuration mode

Explanation

EOS uses a hierarchical CLI similar to other network operating systems; login lands in User EXEC mode where only limited show commands and enable are available. Privileged EXEC requires the enable command. Configuration modes are reached from privileged EXEC.

Question 3Arista EOS and CloudVision Fundamentals

What is the primary purpose of CloudVision in an Arista network?

  1. To centralize management, telemetry, and change workflows across EOS devices Correct answer.
  2. To terminate VPN tunnels at the WAN edge
  3. To replace EOS with a cloud-hosted control plane
  4. To provide layer 2 forwarding on leaf switches

Explanation

CloudVision is a management plane that provides a single pane of glass for configuration, change control, telemetry, and visibility across many EOS devices. It does not perform data-plane forwarding or replace the on-device OS. This separation of management and control/forwarding planes is a core design principle.

Question 4Arista EOS and CloudVision Fundamentals

Which EOS feature allows software upgrades with minimal disruption by restarting individual processes rather than the whole system?

  1. Multi-agent routing
  2. Zero Touch Provisioning
  3. In-service software upgrade (ISSU) Correct answer.
  4. Stateful switchover

Explanation

EOS is built from modular processes, so ISSU can restart or replace components while the system keeps forwarding traffic. This reduces maintenance windows compared with full reboots. ZTP is about initial provisioning, not upgrades.

Question 5Arista EOS and CloudVision Fundamentals

An engineer wants a device to fetch its startup configuration automatically from a server on first boot without manual CLI input. Which EOS capability should be used?

  1. Zero Touch Provisioning (ZTP) Correct answer.
  2. OpenConfig gNMI
  3. Event Monitor
  4. CloudVision change control

Explanation

ZTP lets a factory-default switch obtain an IP address, locate a configuration or script, and apply it automatically at boot. It is the standard mechanism for unattended first-boot provisioning. CloudVision change control manages approved changes but does not by itself perform first-boot bootstrapping.

Question 6Arista EOS and CloudVision Fundamentals

Which statement best describes the relationship between the EOS control plane and data plane?

  1. The control plane builds forwarding state that the data plane uses to move packets Correct answer.
  2. The data plane only exists on virtual platforms
  3. The data plane runs routing protocols and programs the control plane
  4. Both planes run in the same process and cannot be separated

Explanation

In EOS, routing protocols and other control-plane processes compute reachability and program forwarding tables. The data plane (hardware or software forwarding) then uses those tables to move traffic. Keeping the roles distinct is fundamental to the architecture.

Question 7Arista EOS and CloudVision Fundamentals

What does the EOS command 'show version' primarily report?

  1. The current running configuration
  2. The list of configured users
  3. The software image version, hardware model, and uptime Correct answer.
  4. The ARP table entries

Explanation

'show version' displays the EOS software release, hardware platform, serial number, and uptime. It is the standard first check when validating software or hardware details. Configuration, ARP, and user data are shown by other commands.

Question 8Arista EOS and CloudVision Fundamentals

In CloudVision, what is the role of a change control (change management) workflow?

  1. It elects a designated router for multicast
  2. It schedules, reviews, and tracks configuration changes pushed to devices Correct answer.
  3. It assigns IP addresses to newly connected hosts
  4. It encrypts management traffic between switches

Explanation

CloudVision change control provides a structured process to stage, review, approve, and execute changes across devices, with tracking and rollback support. It is about governance and orchestration of configuration, not encryption, addressing, or routing election.

Question 9Arista EOS and CloudVision Fundamentals

Which protocol does CloudVision commonly use to stream telemetry and state from EOS devices?

  1. SNMP traps only
  2. SMTP
  3. gRPC with gNMI Correct answer.
  4. RADIUS

Explanation

EOS supports streaming telemetry using gRPC/gNMI, which pushes structured state and counters to collectors such as CloudVision. SNMP can be used but is poll/trap based and not the primary streaming mechanism. SMTP and RADIUS serve unrelated purposes.

Question 10Arista EOS and CloudVision Fundamentals

Which EOS feature provides a programmatic way to subscribe to system events and trigger CLI actions when conditions are met?

  1. Route redistribution
  2. Port mirroring
  3. Link aggregation
  4. Event Monitor Correct answer.

Explanation

Event Monitor lets an operator define triggers on system events and run CLI commands in response, useful for automated reactions. Port mirroring copies traffic, redistribution shares routes between protocols, and link aggregation bundles links. None of those provide event-driven CLI automation.

Question 11Arista EOS and CloudVision Fundamentals

An administrator needs to compare the running configuration with the startup configuration on an EOS switch. Which command is most appropriate?

  1. show running-config all
  2. show running-config diff
  3. show diff running-config startup-config Correct answer.
  4. show startup-config running-config

Explanation

EOS provides 'show diff' to compare configuration files, for example the running configuration against the startup configuration. This highlights unsaved changes. The other commands display a single configuration or all defaults rather than a diff.

Question 12Arista EOS and CloudVision Fundamentals

What is the function of the EOS 'management API' (eAPI)?

  1. It encrypts all data-plane traffic
  2. It provides DHCP relay services
  3. It replaces the need for a routing protocol
  4. It provides a JSON/XML programmatic interface to run EOS CLI commands over HTTP/HTTPS Correct answer.

Explanation

eAPI exposes EOS CLI commands through structured JSON or XML over HTTP/HTTPS, enabling automation tools to configure and query devices. It is a management interface, not a routing, encryption, or DHCP feature. This makes EOS highly automatable.

Question 13Arista EOS and CloudVision Fundamentals

Which CloudVision component is responsible for collecting and storing telemetry and state from managed devices?

  1. The telemetry and state database services Correct answer.
  2. The switch ASIC
  3. The DHCP server
  4. The CloudVision portal only

Explanation

CloudVision includes backend services that ingest and store streaming telemetry and state from devices, which the portal then presents. The portal is the user interface, and the ASIC is switch hardware. A DHCP server is unrelated to telemetry storage.

Question 14Arista EOS and CloudVision Fundamentals

Which statement about EOS software images is accurate?

  1. EOS does not support virtualization
  2. EOS images can only be upgraded by replacing hardware
  3. EOS uses a single binary image across supported platforms Correct answer.
  4. Each hardware platform requires a completely different EOS codebase

Explanation

EOS is delivered as a single software image that runs across Arista's supported hardware platforms, simplifying version management. Platform-specific behavior is handled at runtime. This single-image model is a defining EOS characteristic.

Question 15Arista EOS and CloudVision Fundamentals

A network team wants devices to validate configuration against a golden intent model before deployment. Which CloudVision capability best supports this?

  1. Spanning Tree root guard
  2. BGP route reflection
  3. Port mirroring sessions
  4. Configuration compliance and change control with intent-based validation Correct answer.

Explanation

CloudVision can compare device configuration against defined intent or compliance policies and gate changes through change control. This supports validating desired state before rollout. Mirroring, root guard, and route reflection are device-level data/control-plane features unrelated to intent validation.

Question 16Arista EOS and CloudVision Fundamentals

Which EOS CLI command saves the running configuration so it persists after a reload?

  1. configure terminal
  2. reload now
  3. write erase
  4. copy running-config startup-config Correct answer.

Explanation

Copying the running configuration to the startup configuration persists changes across reboots. The reload command restarts the device, write erase clears saved configuration, and configure terminal enters configuration mode. Only the copy operation saves state.

Question 17Arista EOS and CloudVision Fundamentals

What does Zero Touch Provisioning rely on to locate its initial configuration during first boot?

  1. A preinstalled static route
  2. An SNMP set request
  3. A manually typed configuration at the console
  4. DHCP options and a reachable provisioning server Correct answer.

Explanation

ZTP uses DHCP to obtain an address and pointers (such as option 67 or vendor options) to a provisioning server, then downloads and applies configuration or scripts. This enables unattended bring-up. Manual typing, preinstalled routes, and SNMP are not part of the ZTP discovery flow.

Question 18Arista EOS and CloudVision Fundamentals

Which EOS capability allows multiple routing protocol processes to run as independent agents while sharing a common forwarding table?

  1. Port channeling
  2. Multi-agent routing architecture Correct answer.
  3. VLAN trunking
  4. Access control lists

Explanation

EOS uses a multi-agent architecture where routing and other protocol processes run independently and program a shared forwarding infrastructure. This modularity improves fault isolation and supports ISSU. Port channels, trunking, and ACLs are forwarding or filtering features, not process architecture.

Question 19Arista EOS and CloudVision Fundamentals

Which interface does an administrator typically use to reach the EOS CLI remotely and securely?

  1. Telnet on port 23
  2. HTTP on port 80
  3. SSH on port 22 Correct answer.
  4. FTP on port 21

Explanation

SSH provides encrypted remote CLI access and is the standard secure management method on EOS. Telnet is unencrypted, HTTP is for web/eAPI access, and FTP is for file transfer. Secure management favors SSH.

Question 20Arista EOS and CloudVision Fundamentals

What is the main benefit of CloudVision's single-pane-of-glass model for a large fabric?

  1. It provides centralized visibility and consistent management across many devices Correct answer.
  2. It removes the need for any per-device configuration
  3. It guarantees zero packet loss during failures
  4. It eliminates the need for routing protocols

Explanation

CloudVision aggregates state and management for many devices into one interface, improving operational consistency and visibility. Devices still run their own configurations and routing, and no tool can guarantee zero loss. The value is centralized operations, not eliminating device roles.

Question 21Arista EOS and CloudVision Fundamentals

An engineer configures a scheduled task in CloudVision to push a VLAN change to 40 switches during a maintenance window. Which two CloudVision concepts are most directly involved?

  1. SNMP polling and syslog
  2. NAT and DHCP
  3. Change control and device tagging/containers Correct answer.
  4. STP and LACP

Explanation

CloudVision uses change control to stage and schedule the rollout and uses device tags or containers to target the correct set of switches. Together they scope and govern the change. The other option pairs are unrelated device protocols.

Question 22Arista EOS and CloudVision Fundamentals

Which command displays the current EOS logging messages buffered on the device?

  1. show mac address-table
  2. show logging Correct answer.
  3. show ip route
  4. show interfaces

Explanation

'show logging' displays buffered syslog messages and logging configuration details. The other commands display interface status, routing table, or MAC table information. Logging output is essential for troubleshooting events.

Question 23Arista EOS and CloudVision Fundamentals

Which statement best explains why EOS separates individual protocol processes?

  1. It forces all protocols to share a single thread
  2. It removes the need for a forwarding table
  3. It allows a failing process to be restarted without rebooting the entire switch Correct answer.
  4. It reduces the number of physical interfaces required

Explanation

Running protocols as separate processes means a fault or restart in one agent does not require a full system reboot, improving availability. It does not change physical interface counts or eliminate forwarding tables. Sharing a single thread would contradict the modular design.

Question 24Arista EOS and CloudVision Fundamentals

What does the EOS command 'show running-config' display?

  1. The currently active configuration in memory Correct answer.
  2. The device's hardware inventory
  3. The saved startup configuration only
  4. The list of open TCP sessions

Explanation

'show running-config' shows the configuration currently active in the device's memory, including unsaved changes. The startup configuration is what persists after reload, and hardware or session data come from other commands. Comparing the two helps detect unsaved edits.

Question 25Arista EOS and CloudVision Fundamentals

A team wants automation scripts to configure EOS devices using structured data without screen-scraping CLI text. Which approach aligns best with Arista's automation model?

  1. Using eAPI or gNMI to send structured requests and parse structured responses Correct answer.
  2. Using SNMP sets for all configuration
  3. Using FTP to upload configuration text
  4. Using Telnet and parsing raw terminal output

Explanation

eAPI and gNMI return structured JSON or protobuf data, which is far more reliable for automation than parsing CLI text. Screen-scraping over Telnet is brittle and insecure. SNMP sets and FTP uploads are not the preferred structured automation path.

Question 26Arista EOS and CloudVision Fundamentals

On an Arista switch, which component is responsible for making forwarding decisions for transit traffic?

  1. The orchestration plane
  2. The data plane Correct answer.
  3. The control plane
  4. The management plane

Explanation

The data plane (forwarding plane) performs the actual packet forwarding decisions in hardware. The control plane builds the tables the data plane uses, but it does not forward transit traffic itself.

Question 27Arista EOS and CloudVision Fundamentals

Which Arista feature lets a switch act as a single logical control point for a set of switches while still running EOS on each member?

  1. CloudVision
  2. LANZ
  3. Multi-node EOS (vEOS-lab)
  4. MLAG Correct answer.

Explanation

MLAG lets two switches present a single logical L2 endpoint to downstream devices by synchronizing control information over a peer link. Each switch still runs its own EOS instance and forwards independently.

Question 28Arista EOS and CloudVision Fundamentals

What is the primary purpose of the EOS state database (Sysdb) in the system architecture?

  1. It caches ARP entries learned from the data plane.
  2. It holds the licensing entitlements for the device.
  3. It stores the startup configuration file on flash.
  4. It provides a central, structured store of system state that agents read and write. Correct answer.

Explanation

Sysdb is a central in-memory state store that EOS agents publish to and subscribe from, decoupling producers of state from consumers. This lets CLI, APIs, and telemetry read consistent state rather than parsing each other's output.

Question 29Arista EOS and CloudVision Fundamentals

Which statement describes how EOS handles a failing routing protocol process?

  1. Only the affected protocol agent restarts while other agents keep running. Correct answer.
  2. The entire switch reloads to recover the process.
  3. All protocol agents are restarted together to keep state consistent.
  4. The data plane stops forwarding until the process recovers.

Explanation

EOS runs protocols as independent agents, so a fault in one agent can be isolated and restarted without reloading the system or disturbing other agents. Forwarding already installed in hardware typically continues during that restart.

Question 30Arista EOS and CloudVision Fundamentals

Which CloudVision service is the entry point that exposes a REST API for provisioning, telemetry, and change management?

  1. CloudVision Telemetry (CVT)
  2. CloudVision eXchange (CVX)
  3. CloudVision Portal (CVP) Correct answer.
  4. CloudVision Configlet (CVC)

Explanation

CloudVision Portal is the management application and northbound API surface used for provisioning, telemetry visualization, and change control. Other named components serve more specialized roles such as control-plane services or telemetry collection.

Question 31Arista EOS and CloudVision Fundamentals

Which protocol is used by EOS devices to communicate with CloudVision for streaming telemetry and state?

  1. OpenConfig gNMI over gRPC Correct answer.
  2. LLDP
  3. RADIUS
  4. SNMP

Explanation

EOS streams telemetry to CloudVision using OpenConfig models delivered over gNMI/gRPC, which supports structured, high-frequency data. SNMP is poll-based and not the streaming mechanism used by CloudVision.

Question 32Arista EOS and CloudVision Fundamentals

What is the function of a configlet in CloudVision?

  1. A license file installed to enable advanced features.
  2. A scheduled packet capture taken from a device.
  3. A template of configuration lines applied to devices based on tags or containers. Correct answer.
  4. A backup copy of a device's flash filesystem.

Explanation

Configlets are reusable configuration templates that CloudVision maps to devices through tags, containers, or static assignment. They let administrators apply consistent configuration at scale rather than editing each device individually.

Question 33Arista EOS and CloudVision Fundamentals

Which EOS command shows the status of hardware forwarding table utilization, such as routes and next-hop entries?

  1. show version
  2. show ip route summary
  3. show platform fap Correct answer.
  4. show logging

Explanation

The 'show platform fap' command reports forwarding ASIC resource utilization, including routes, next hops, and other table usage. This helps engineers confirm hardware capacity before or after scale changes.

Question 34Arista EOS and CloudVision Fundamentals

An engineer wants to verify which EOS agents are currently running and their resource usage. Which command is most appropriate?

  1. show running-config
  2. show interfaces status
  3. show processes top Correct answer.
  4. show vrrp

Explanation

'show processes top' displays running processes with CPU and memory information, which is how an administrator inspects agent health and resource use. Other commands address interface, configuration, or protocol state rather than process status.

Question 35Arista EOS and CloudVision Fundamentals

Which statement describes the role of the EOS management interface (Management1) in a production switch?

  1. It is used exclusively for stacking multiple switches.
  2. It automatically load-balances data-plane traffic.
  3. It provides an out-of-band path for administrative access and management traffic. Correct answer.
  4. It carries all transit user traffic between other switches.

Explanation

Management1 is a dedicated out-of-band interface used for administrative access such as SSH, eAPI, and telemetry. Keeping management traffic separate from transit traffic improves security and operational resilience.

Question 36Arista EOS and CloudVision Fundamentals

Which EOS feature allows a network engineer to run commands and retrieve structured JSON output programmatically?

  1. LANZ
  2. eAPI Correct answer.
  3. MLAG
  4. VRRP

Explanation

eAPI exposes EOS CLI commands over HTTP/HTTPS and can return structured JSON, enabling automation without screen-scraping text. The other features provide redundancy, monitoring, or availability functions rather than a programmatic interface.

Question 37Arista EOS and CloudVision Fundamentals

Which EOS feature provides a single point of control for VXLAN bridging and routing in a large data-center fabric?

  1. LANZ
  2. MLAG
  3. CloudVision eXchange (CVX) Correct answer.
  4. VARP

Explanation

CVX provides centralized control-plane services for VXLAN, including bridging and routing functions across a fabric. MLAG, VARP, and LANZ address redundancy, gateway availability, and monitoring rather than VXLAN control.

Question 38Arista EOS and CloudVision Fundamentals

What is the purpose of the 'show tech-support' command on an EOS device?

  1. It resets the switch to factory defaults.
  2. It displays the current license entitlements.
  3. It collects a bundle of diagnostic output for troubleshooting and support. Correct answer.
  4. It enables debug logging for all agents.

Explanation

'show tech-support' gathers comprehensive diagnostic information from many subsystems into a bundle useful for support cases. It does not alter device state or configuration.

Question 39Arista EOS and CloudVision Fundamentals

An engineer needs to reboot an EOS switch into a specific saved configuration file. Which approach best accomplishes this?

  1. Delete the running-config and reload the device.
  2. Run 'show reload' and reload the device.
  3. Copy the file to startup-config and reload the device. Correct answer.
  4. Run 'clear counters' and reload the device.

Explanation

EOS loads the startup-config at boot, so placing the desired file in startup-config and reloading applies it. Clearing counters or displaying reload information does not change which configuration is loaded.

Question 40Arista EOS and CloudVision Fundamentals

Which statement best describes the relationship between EOS running-config and startup-config?

  1. The running-config is active in memory; startup-config is loaded at boot until explicitly saved. Correct answer.
  2. Both files are stored in the same location and updated by the same command.
  3. They are always identical because EOS writes changes to startup-config immediately.
  4. The startup-config is active in memory while running-config is stored on flash.

Explanation

Changes made in the CLI affect the running-config in memory and take effect immediately, but they persist across reloads only when saved to startup-config. This is why unsaved changes are lost after a reboot.

Question 41Arista EOS and CloudVision Fundamentals

Which command on EOS displays the current interface counters and error statistics for a specific Ethernet port?

  1. show mac address-table
  2. show ntp status
  3. show interfaces Ethernet1 counters Correct answer.
  4. show ip interface brief

Explanation

The 'show interfaces <name> counters' command reports packet and error counters for that interface. It is the standard way to check whether an interface is dropping or erroring traffic.

Question 42Arista EOS and CloudVision Fundamentals

Which EOS capability supports loading an alternate software image and reverting if the new image fails to boot?

  1. VXLAN overlay
  2. Dual flash partitions for EOS images Correct answer.
  3. MLAG peer fallback
  4. Dual supervisor modules

Explanation

EOS supports multiple image partitions so a new image can be installed and booted while the previous image remains available for rollback. This reduces risk during upgrades.

Question 43Arista EOS and CloudVision Fundamentals

What is the main benefit of using CloudVision tags and containers when managing a fabric?

  1. They replace the need for routing protocols in the fabric.
  2. They provide hardware redundancy for leaf switches.
  3. They group devices logically so policies and configlets can be applied at scale. Correct answer.
  4. They encrypt management traffic between devices.

Explanation

Tags and containers create logical groupings of devices, letting administrators apply configlets and policies to many devices at once. This scales management without per-device configuration.

Question 44Arista EOS and CloudVision Fundamentals

Which EOS command sequence enables the eAPI over HTTPS?

  1. interface Management1 followed by ip address
  2. logging console followed by severity informational
  3. management api http-commands followed by no shutdown Correct answer.
  4. router bgp followed by neighbor activate

Explanation

eAPI is enabled by entering 'management api http-commands' configuration mode and ensuring the service is not shut down. The other sequences configure routing, addressing, or logging, which are unrelated to enabling eAPI.

Question 45Arista EOS and CloudVision Fundamentals

Which statement describes the role of CloudVision's change control feature when deploying configuration to many devices?

  1. It only backs up device configurations and cannot push changes.
  2. It automatically approves and pushes changes without any review.
  3. It stages changes, requires approval, and executes them in a controlled sequence. Correct answer.
  4. It replaces configlets with manual CLI edits on each device.

Explanation

Change controls provide a workflow where proposed changes are reviewed and approved before execution, with tracked results across devices. This reduces the risk of uncoordinated changes in large fabrics.

Question 46Arista EOS and CloudVision Fundamentals

An engineer wants to confirm that EOS is forwarding traffic in hardware for a specific prefix. Which command best shows the hardware forwarding entry?

  1. show running-config
  2. show ip route
  3. show arp
  4. show ip hardware fib Correct answer.

Explanation

The hardware FIB view shows entries programmed into the forwarding ASIC, confirming hardware forwarding for a prefix. The routing table shows control-plane routes, which may not reflect what is installed in hardware.

Question 47Arista EOS and CloudVision Fundamentals

Which statement best explains why EOS exposes structured JSON output from many show commands?

  1. It encrypts the output for secure transport.
  2. It allows automation tools to consume data reliably without parsing human-formatted text. Correct answer.
  3. It automatically applies configuration changes.
  4. It reduces the amount of information returned by the command.

Explanation

Structured output provides stable, machine-readable fields that automation can consume without fragile text parsing. It does not change the underlying data or apply configuration.

Question 48Arista EOS and CloudVision Fundamentals

Which EOS feature is used to monitor queue latency and congestion in real time?

  1. VARP
  2. LANZ Correct answer.
  3. MLAG
  4. eAPI

Explanation

LANZ provides real-time latency and congestion monitoring of queues, helping identify microbursts and buffer pressure. The other features provide redundancy, gateway availability, or programmatic access.

Question 49Arista EOS and CloudVision Fundamentals

Which statement describes how Zero Touch Provisioning obtains its initial configuration on first boot?

  1. It uses the last known configuration from a neighboring switch.
  2. It loads configuration from a USB drive only.
  3. It discovers a provisioning source over the network and downloads configuration or a script. Correct answer.
  4. It requires an administrator to type the full configuration at the console.

Explanation

ZTP automates first-boot provisioning by discovering a source such as a DHCP server and downloading a configuration or script. This lets new devices be deployed without manual console configuration.

Question 50Arista EOS and CloudVision Fundamentals

Which EOS command displays the current system time source and synchronization status?

  1. show clock
  2. show version
  3. show logging
  4. show ntp status Correct answer.

Explanation

'show ntp status' reports whether the device is synchronized and which time source it is using. 'show clock' displays the current time but not the synchronization source details.