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Arista Foundations study materials
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Arista Foundations practice questions

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Question 1EOS and Cloud Networking Fundamentals

Which Arista EOS feature provides a single, unified management interface that presents a consistent CLI and API across all Arista switches regardless of underlying hardware?

  1. A proprietary ASIC abstraction layer
  2. A centralized controller appliance
  3. A common EOS software architecture Correct answer.
  4. A shared Linux kernel image

Explanation

EOS is built as a single software image with a common architecture that runs across all Arista platforms, so the CLI, APIs, and behavior stay consistent. Hardware-specific drivers sit beneath this common layer rather than replacing it.

Question 2EOS and Cloud Networking Fundamentals

In EOS, which command-line mode allows an operator to view configuration and status but not change the running configuration?

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

Explanation

Privileged EXEC mode (the '#' prompt) is for show commands and monitoring; configuration changes require entering global configuration mode with 'configure terminal'.

Question 3EOS and Cloud Networking Fundamentals

An engineer wants to save the current running configuration so it persists after a reload. Which EOS command accomplishes this?

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

Explanation

Copying the running configuration to the startup configuration writes it to persistent storage so it is loaded at next boot. The running configuration alone is lost on reload.

Question 4EOS and Cloud Networking Fundamentals

Which protocol does Arista EOS use by default to synchronize configuration and operational state across switches in an MLAG pair?

  1. OSPF
  2. BGP
  3. STP
  4. MLAG peer link with in-band control Correct answer.

Explanation

MLAG peers exchange control information over a dedicated peer link (and peer-link-related in-band management) to keep their forwarding state synchronized. Routing protocols and STP are not the synchronization mechanism for MLAG.

Question 5EOS and Cloud Networking Fundamentals

What is the primary purpose of Arista's CloudVision platform?

  1. To terminate IPsec tunnels between data centers
  2. To act as a hardware load balancer for server farms
  3. To provide centralized management, telemetry, and automation across an EOS fabric Correct answer.
  4. To replace the need for any local switch configuration files

Explanation

CloudVision is a management and telemetry platform that centralizes configuration, change management, and streaming telemetry for EOS devices. It complements rather than eliminates device-level configuration.

Question 6EOS and Cloud Networking Fundamentals

Which EOS mechanism streams near-real-time operational data to external collectors without repeated polling?

  1. NetFlow
  2. Syslog
  3. Streaming telemetry Correct answer.
  4. SNMP traps

Explanation

Streaming telemetry pushes structured operational data to collectors on a schedule or on change, avoiding the overhead of repeated polling. SNMP and syslog are event- or poll-based and less granular.

Question 7EOS and Cloud Networking Fundamentals

An operator needs to apply a configuration change to many EOS switches at once using a repeatable, version-controlled method. Which approach best fits Arista's automation model?

  1. Manual CLI entry on each device
  2. Using only SNMP set operations
  3. Copying a text file to each device by hand
  4. eAPI with a scripting or automation tool Correct answer.

Explanation

EOS eAPI exposes CLI commands over JSON/HTTP(S), enabling programmatic, repeatable automation from scripts or tools. Manual entry and file copying are not repeatable or version-controlled.

Question 8EOS and Cloud Networking Fundamentals

Which statement best describes Arista's approach to software-defined networking in the data center?

  1. It depends on spanning tree to build loop-free topologies
  2. It requires replacing all switches with software virtual switches
  3. It uses a leaf-spine fabric with distributed control and programmable APIs Correct answer.
  4. It relies exclusively on a centralized SDN controller for all forwarding decisions

Explanation

Arista's data center designs use leaf-spine topologies with routing protocols and programmable APIs, keeping control distributed while enabling automation. Spanning tree is avoided in favor of routed fabrics.

Question 9EOS and Cloud Networking Fundamentals

In a leaf-spine fabric, what is the primary role of the spine layer?

  1. To host the management plane
  2. To provide high-bandwidth interconnection between all leaf switches Correct answer.
  3. To connect servers directly to the fabric
  4. To terminate all storage traffic

Explanation

Spines interconnect leaves so any leaf can reach any other leaf in a predictable number of hops. Servers connect to leaves, not spines.

Question 10EOS and Cloud Networking Fundamentals

Why is a routed leaf-spine design often preferred over a large Layer 2 domain in a data center?

  1. It provides predictable equal-cost multipathing and limits failure domains Correct answer.
  2. It eliminates the need for IP addressing
  3. It guarantees zero packet loss
  4. It removes the need for any routing protocol

Explanation

A routed fabric uses ECMP for predictable bandwidth utilization and confines failures to smaller domains than a large Layer 2 domain. It still requires IP addressing and routing protocols.

Question 11EOS and Cloud Networking Fundamentals

What does VXLAN provide in a data center overlay network?

  1. Layer 2 extension over a Layer 3 underlay using MAC-in-UDP encapsulation Correct answer.
  2. A replacement for BGP in the underlay
  3. A hardware-only switching mode
  4. A method to compress IP headers

Explanation

VXLAN encapsulates Layer 2 frames in UDP, allowing Layer 2 segments to span a Layer 3 underlay with a large 24-bit segment identifier space. It works with, not instead of, underlay routing.

Question 12EOS and Cloud Networking Fundamentals

In an EVPN-VXLAN fabric, what role does EVPN play?

  1. It distributes MAC and IP reachability information via BGP Correct answer.
  2. It replaces the need for any underlay routing
  3. It encrypts tenant traffic end to end
  4. It provides the data-plane encapsulation

Explanation

EVPN is a control-plane solution that advertises MAC and IP reachability through BGP extensions, enabling efficient VXLAN tunneling. Encapsulation itself is done by VXLAN.

Question 13EOS and Cloud Networking Fundamentals

Which Arista feature allows a switch to be managed and provisioned automatically on first boot using a configuration served over the network?

  1. MLAG
  2. VARP
  3. Zero Touch Provisioning Correct answer.
  4. sFlow

Explanation

Zero Touch Provisioning (ZTP) lets a new switch fetch and apply configuration automatically at first boot. MLAG, VARP, and sFlow serve other purposes.

Question 14EOS and Cloud Networking Fundamentals

What is the function of Arista's Virtual ARP (VARP) feature?

  1. To provide a shared virtual IP default gateway across multiple switches Correct answer.
  2. To translate MAC addresses into IP addresses
  3. To encrypt ARP traffic
  4. To replace routing protocols in the underlay

Explanation

VARP lets multiple switches share a virtual IP and MAC for the default gateway, providing redundancy without a dedicated gateway protocol. It does not translate or encrypt addresses.

Question 15EOS and Cloud Networking Fundamentals

An engineer wants two switches to act as a single logical device for link aggregation to attached servers while keeping independent control planes. Which Arista feature fits?

  1. Stacking with a single control plane
  2. MLAG Correct answer.
  3. VXLAN
  4. BGP confederation

Explanation

MLAG lets two switches present a logical link aggregation endpoint to servers while each switch keeps its own control plane. Stacking merges control planes, which is different.

Question 16EOS and Cloud Networking Fundamentals

Which statement about Arista EOS's use of Linux is accurate?

  1. EOS uses Linux only for logging
  2. EOS cannot run third-party Linux applications
  3. EOS is a completely proprietary kernel with no Linux base
  4. EOS runs on a standard Linux kernel with Arista processes on top Correct answer.

Explanation

EOS is built on a standard Linux kernel, with Arista's networking processes running as part of the system. This foundation supports tools and extensibility on the device.

Question 17EOS and Cloud Networking Fundamentals

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

  1. The routing table contents
  2. The list of configured users
  3. The current running configuration
  4. The software image version and hardware details Correct answer.

Explanation

'Show version' displays the EOS software version, hardware platform, and related system details. Configuration and routing tables are shown by other commands.

Question 18EOS and Cloud Networking Fundamentals

Which EOS API transport does eAPI use to expose CLI commands to automation tools?

  1. SSH only
  2. JSON over HTTP or HTTPS Correct answer.
  3. SNMP over UDP
  4. Telnet only

Explanation

eAPI exposes CLI commands as JSON over HTTP or HTTPS, making them consumable by scripts and automation platforms. SSH and SNMP serve different management needs.

Question 19EOS and Cloud Networking Fundamentals

In a VXLAN overlay, what is a VTEP?

  1. A type of access control list
  2. A spanning tree root bridge
  3. An endpoint that encapsulates and decapsulates VXLAN frames Correct answer.
  4. A routing protocol used in the underlay

Explanation

A VXLAN Tunnel Endpoint (VTEP) performs the encapsulation and decapsulation of frames into and out of VXLAN tunnels. It is typically a switch or virtual switch.

Question 20EOS and Cloud Networking Fundamentals

Why does a leaf-spine fabric commonly use ECMP?

  1. To eliminate the need for IP addressing
  2. To elect a single best path and discard the rest
  3. To spread traffic across multiple equal-cost paths for better utilization Correct answer.
  4. To provide encryption between leaves

Explanation

ECMP distributes traffic across multiple equal-cost paths, improving bandwidth utilization and resilience in a fabric. It does not discard paths or provide encryption.

Question 21EOS and Cloud Networking Fundamentals

An operator needs to confirm which interfaces are currently up and their link speeds. Which EOS command is most appropriate?

  1. show users
  2. show interfaces status Correct answer.
  3. show ip route
  4. show running-config

Explanation

'Show interfaces status' summarizes interface state, link status, and speed in a compact table. The other commands report configuration, routes, or sessions.

Question 22EOS and Cloud Networking Fundamentals

What advantage does a containerized EOS (cEOS) offer for testing and automation?

  1. It only supports Layer 1 switching
  2. It runs EOS as a container for lab and CI environments Correct answer.
  3. It requires dedicated physical hardware to run
  4. It removes the need for any configuration

Explanation

cEOS packages EOS as a container, enabling labs and CI pipelines to test configurations without dedicated hardware. It still requires configuration and supports normal EOS features.

Question 23EOS and Cloud Networking Fundamentals

In an EVPN-VXLAN fabric, what is the role of the underlay network?

  1. To distribute MAC addresses between tenants
  2. To encrypt tenant payloads
  3. To carry encapsulated VXLAN traffic between VTEPs using IP routing Correct answer.
  4. To provide the virtual gateway for hosts

Explanation

The underlay provides IP reachability between VTEPs so encapsulated VXLAN traffic can traverse the fabric. MAC distribution is handled by the EVPN control plane.

Question 24EOS and Cloud Networking Fundamentals

Which statement best describes the relationship between CloudVision and streaming telemetry?

  1. CloudVision replaces telemetry with SNMP polling only
  2. CloudVision can collect and visualize telemetry streamed from EOS devices Correct answer.
  3. Telemetry requires disabling CloudVision
  4. Streaming telemetry cannot be consumed by CloudVision

Explanation

CloudVision ingests streaming telemetry from EOS devices and provides visualization and analysis. It does not replace telemetry with polling or require it to be disabled.

Question 25EOS and Cloud Networking Fundamentals

Which Arista capability allows configuration state to be validated and compared against a known-good baseline across a fabric?

  1. Relying on spanning tree recalculation
  2. Configuration backup and comparison features in CloudVision Correct answer.
  3. Using only console access
  4. Disabling all logging

Explanation

CloudVision can back up configurations and compare device state against a baseline, helping detect drift. The other options do not provide validation or comparison.

Question 26EOS and Cloud Networking Fundamentals

Which EOS feature lets a switch run standard Linux tools and third-party software alongside EOS routing processes?

  1. The boot flash partition table
  2. The hardware forwarding ASIC pipeline
  3. The Linux-based EOS architecture with its underlying kernel and package environment Correct answer.
  4. The fan tray controller firmware

Explanation

EOS is built on an unmodified Linux kernel, so standard Linux utilities and packaged applications can run on the switch alongside EOS control-plane processes. The ASIC pipeline, flash layout, and fan controller are hardware or low-level concerns, not a software extensibility mechanism.

Question 27EOS and Cloud Networking Fundamentals

Which EOS command displays the running configuration currently active in the switch?

  1. show running-config Correct answer.
  2. show version
  3. show boot-config
  4. show startup-config

Explanation

The running configuration is the set of commands currently in effect in the control plane and is displayed with show running-config. Startup-config reflects what will load at next boot, and the other commands report image or boot information.

Question 28EOS and Cloud Networking Fundamentals

What does the EOS command 'show interfaces status' primarily display?

  1. A one-line summary of each interface's link state, speed, and VLAN Correct answer.
  2. The ARP entries learned on each interface
  3. Per-interface counters for errors and discards
  4. The spanning tree state of each VLAN

Explanation

show interfaces status gives a compact table of interfaces with their connection state, speed, and assigned VLAN, which is useful for a quick health check. Detailed counters, spanning tree detail, and ARP entries come from other commands.

Question 29EOS and Cloud Networking Fundamentals

In an EVPN-VXLAN fabric, which component is responsible for encapsulating tenant traffic into VXLAN tunnels?

  1. The route reflector
  2. The DHCP relay agent
  3. The VTEP on the leaf switch Correct answer.
  4. The spine's fabric ASIC

Explanation

A VTEP performs the VXLAN encapsulation and decapsulation of tenant frames, typically at the leaf where the host attaches. Route reflectors distribute BGP EVPN routes, spines forward the encapsulated packets, and DHCP relay is unrelated to tunneling.

Question 30EOS and Cloud Networking Fundamentals

Which protocol does an EVPN control plane most commonly use to distribute MAC and IP reachability information?

  1. IS-IS
  2. OSPFv2
  3. BGP with EVPN address family Correct answer.
  4. PIM-SM

Explanation

EVPN is defined as an address family carried in BGP, which distributes MAC and IP reachability along with other route types. OSPF, IS-IS, and PIM are used for underlay routing or multicast, not for EVPN route distribution.

Question 31EOS and Cloud Networking Fundamentals

What is the primary purpose of an MLAG domain in a data center design?

  1. To provide two switches that present a single logical L2 device to attached hosts Correct answer.
  2. To encrypt traffic between racks
  3. To synchronize clocks across the fabric
  4. To replace BGP with a single routing protocol

Explanation

MLAG lets two switches share a logical link-aggregation view so a dual-homed host can use active-active links without spanning tree blocking. It operates at Layer 2, does not replace routing protocols, and does not provide encryption or clock sync.

Question 32EOS and Cloud Networking Fundamentals

Which statement accurately describes CloudVision in an Arista environment?

  1. It is a management platform that provides fabric-wide visibility, provisioning, and change control Correct answer.
  2. It is a routing protocol used between spine and leaf switches
  3. It is a hardware module installed in every leaf switch
  4. It is a packet capture tool that runs only on the spine

Explanation

CloudVision is a management and telemetry platform that centralizes visibility, provisioning, and workflow control across many devices. It is not a routing protocol, it is not a per-switch hardware module, and it is not a spine-only capture utility.

Question 33EOS and Cloud Networking Fundamentals

What does the EOS command 'show ip route' display?

  1. The routing table entries the switch uses for forwarding Correct answer.
  2. The ARP cache for all interfaces
  3. The status of BGP neighbors
  4. The list of configured VLANs

Explanation

show ip route shows the installed IPv4 routing table used for forwarding decisions. ARP, VLAN configuration, and BGP neighbor status are each shown by their own dedicated commands.

Question 34EOS and Cloud Networking Fundamentals

An engineer wants EOS to send a syslog message to a central server. Which configuration step accomplishes this?

  1. Configure a VRF named after the server
  2. Configure a loopback with the server's address
  3. Configure a default gateway pointing at the server
  4. Configure logging host with the server's IP address Correct answer.

Explanation

The logging host command directs EOS to send syslog messages to the specified remote collector. A loopback, default gateway, or VRF name does not by itself forward log messages to a server.

Question 35EOS and Cloud Networking Fundamentals

A network team is comparing a routed leaf-spine fabric with a traditional large Layer 2 core. Which characteristic favors the routed fabric?

  1. It relies on a single spanning tree instance to prevent loops
  2. It avoids the need for any IP addressing scheme
  3. It limits failure domains and uses multipath routing for bandwidth Correct answer.
  4. It requires larger broadcast domains for scale

Explanation

A routed fabric confines Layer 2 domains and uses routing protocols with multipath forwarding such as ECMP to use all links. Large Layer 2 designs depend on spanning tree, which blocks redundant paths and enlarges broadcast domains.

Question 36EOS and Cloud Networking Fundamentals

A server is dual-homed to two MLAG peers. What must be consistent on both peers for the MLAG to form correctly?

  1. The SNMP community string
  2. The hostname of each switch
  3. The MLAG domain identifier and the interface configuration for the shared links Correct answer.
  4. The management IP address of each switch

Explanation

MLAG peers must share a matching domain identifier and consistent configuration on the member interfaces so the pair presents one logical view. Hostnames, management addresses, and SNMP strings are local settings that do not need to match.

Question 37EOS and Cloud Networking Fundamentals

What is the function of a VXLAN network identifier (VNI) in an overlay?

  1. It defines the BGP autonomous system number
  2. It segments tenant Layer 2 domains across the shared underlay Correct answer.
  3. It sets the MTU for the underlay links
  4. It identifies the physical uplink used for a tenant

Explanation

The VNI is a 24-bit identifier that segments tenant Layer 2 networks carried over a shared IP underlay, allowing many isolated domains. It does not select physical uplinks, define BGP AS numbers, or configure MTU.

Question 38EOS and Cloud Networking Fundamentals

In an EVPN-VXLAN fabric, why is BGP commonly used as the underlay routing protocol?

  1. It encrypts all traffic between the leaves
  2. It replaces the need for a control plane overlay
  3. It eliminates the need for IP addressing on the leaves
  4. It provides multipath forwarding with ECMP across all spine links Correct answer.

Explanation

BGP supports multipath and ECMP so traffic can be load-shared across all available spine links, which suits a leaf-spine underlay. It does not remove addressing needs, encrypt traffic, or eliminate the overlay control plane.

Question 39EOS and Cloud Networking Fundamentals

An operator wants to verify that a leaf has formed BGP EVPN peering with its route reflectors. Which EOS command is most useful?

  1. show mac address-table
  2. show interfaces status
  3. show vlan
  4. show ip bgp summary Correct answer.

Explanation

show ip bgp summary reports BGP neighbor states and prefix counts, which reveals whether EVPN peers are established. Interface status, VLAN lists, and the MAC table do not show BGP peering state.

Question 40EOS and Cloud Networking Fundamentals

What does the EOS command 'show lldp neighbors' help an operator confirm?

  1. Which VLANs are allowed on a trunk
  2. Which routes are installed in the FIB
  3. Which devices are directly connected on each port Correct answer.
  4. Which users are logged into the switch

Explanation

LLDP advertises identity and port information to directly connected neighbors, so this command reveals the adjacent device on each link. Routes, VLAN membership, and user sessions are shown by other commands.

Question 41EOS and Cloud Networking Fundamentals

A design team is choosing between a VXLAN overlay and a traditional VLAN-stretched design across two data centers. Which advantage does the overlay provide?

  1. It removes the need for any routing protocol
  2. It guarantees lower latency than a direct fiber link
  3. It carries Layer 2 segments over a Layer 3 underlay without stretching spanning tree Correct answer.
  4. It requires fewer IP addresses on the underlay

Explanation

VXLAN encapsulates Layer 2 frames in IP packets so segments can extend across a routed underlay without extending spanning tree domains. It does not reduce underlay addressing needs, remove routing, or guarantee lower latency.

Question 42EOS and Cloud Networking Fundamentals

Which EOS feature provides a per-interface view of received and transmitted packet rates for troubleshooting congestion?

  1. show running-config
  2. show hostname
  3. show interfaces counters rates Correct answer.
  4. show ip route

Explanation

The counters rates command reports current per-interface traffic rates, which helps spot congested or saturated links. Configuration, routing, and hostname commands do not report traffic rates.

Question 43EOS and Cloud Networking Fundamentals

What is the role of a route reflector in an EVPN fabric?

  1. It assigns IP addresses to hosts
  2. It forwards tenant data traffic between VTEPs
  3. It performs VXLAN decapsulation for remote subnets
  4. It reflects EVPN routes among BGP peers so every leaf does not need a full mesh Correct answer.

Explanation

A route reflector receives EVPN routes and reflects them to other peers, avoiding the need for a full BGP mesh among leaves. Data forwarding, address assignment, and decapsulation are handled by other components.

Question 44EOS and Cloud Networking Fundamentals

An engineer needs to confirm which software image and boot parameters a switch will use after the next reload. Which command is appropriate?

  1. show interfaces status
  2. show ip arp
  3. show vlan
  4. show boot-config Correct answer.

Explanation

show boot-config reports the software image and boot parameters that will be used at startup. The other commands report interface state, ARP entries, and VLAN configuration.

Question 45EOS and Cloud Networking Fundamentals

A team wants to automate configuration of many EOS switches from a central tool using structured data. Which EOS capability best supports this?

  1. The eAPI interface that exposes CLI commands over HTTP or HTTPS Correct answer.
  2. The spanning tree topology database
  3. The MAC address table
  4. The LLDP neighbor table

Explanation

eAPI exposes EOS CLI commands through HTTP or HTTPS so automation tools can send and receive structured data programmatically. LLDP, MAC tables, and spanning tree databases are operational data sources, not automation interfaces.

Question 46EOS and Cloud Networking Fundamentals

In a VXLAN overlay, what happens to the original Ethernet frame when a VTEP sends it into a tunnel?

  1. It is compressed and sent as a single IP packet without a tunnel header
  2. It is discarded and replaced by a routing update
  3. It is encapsulated with outer IP and UDP headers plus a VXLAN header Correct answer.
  4. It is converted into a BGP update message

Explanation

The VTEP wraps the original frame in a VXLAN header, then UDP and outer IP headers so it can traverse the routed underlay to the remote VTEP. The frame is not discarded, compressed away, or converted into a routing update.

Question 47EOS and Cloud Networking Fundamentals

A leaf-spine fabric uses ECMP for underlay forwarding. What determines which spine a given flow takes?

  1. A hash of packet header fields such as source and destination addresses and ports Correct answer.
  2. The BGP router ID of the leaf
  3. The source MAC address only
  4. The VNI assigned to the tenant

Explanation

ECMP hashes selected header fields so that flows are distributed across available equal-cost paths while keeping a flow on one path for consistency. Source MAC alone, the VNI, and the router ID are not the hashing inputs for path selection.

Question 48EOS and Cloud Networking Fundamentals

An operator observes that an MLAG member link is down but traffic continues to flow. What is the most likely explanation?

  1. The switch has entered a reboot loop
  2. The failed link is still forwarding because of spanning tree
  3. The peer link and remaining member links carry traffic while the failed link is removed from the aggregate Correct answer.
  4. The MLAG domain has automatically converted to a routed fabric

Explanation

An MLAG aggregate continues forwarding over the remaining member links and the peer link when one member fails, so service is maintained with reduced capacity. The domain does not become a routed fabric, a down link cannot forward, and a reboot loop would disrupt service.

Question 49EOS and Cloud Networking Fundamentals

A design review notes that the underlay MTU must accommodate VXLAN overhead. Why does this matter?

  1. Encapsulation adds outer headers, so underlay links need a larger MTU than tenant frames Correct answer.
  2. VXLAN compresses frames and requires a smaller MTU
  3. BGP updates require jumbo frames to converge
  4. The VNI field consumes the entire payload

Explanation

VXLAN adds a VXLAN header plus UDP and outer IP headers, so the underlay must carry a larger packet than the original tenant frame to avoid fragmentation or drops. VXLAN does not compress frames, BGP convergence does not require jumbo frames, and the VNI is a small header field.

Question 50EOS and Cloud Networking Fundamentals

An engineer wants to compare the intended configuration of a switch with its live state to detect drift. Which approach fits an Arista workflow?

  1. Use the MAC address table as the source of truth
  2. Capture the running configuration and compare it with a stored baseline or use a management platform that tracks configuration state Correct answer.
  3. Rely on LLDP neighbor output as the configuration record
  4. Read the fan tray status to infer configuration changes

Explanation

Configuration drift detection compares the live running configuration against a stored baseline or uses a management platform that tracks and validates intended state. LLDP, MAC tables, and fan status describe operational conditions rather than configuration.