Question 1

How many Arista switches may be a part of a single MLAG domain?

Accepted Answer

A

Explanation: An Arista Multi-Chassis Link Aggregation (MLAG) domain is fundamentally designed as a high-availability pair. It consists of exactly two Arista switches, referred to as MLAG peers. These peers are connected via a dedicated peer-link and synchronize their state information, such as MAC address tables and LACP states, using the MLAG control protocol. This architecture allows the two physical switches to function as a single logical switch from the perspective of a connected device, enabling active-active forwarding, device-level redundancy, and hitless software upgrades. The core design of the MLAG protocol is based on this two-switch pairing.

Question 2

How many Virtual Network Identifiers are supported by the VXLAN specification?

Accepted Answer

C

Explanation: The VXLAN (Virtual Extensible LAN) specification, defined in IETF RFC 7348, uses a 24-bit field for the VXLAN Network Identifier (VNI). This 24-bit identifier space allows for a theoretical maximum of 2^24 unique virtual networks. Calculating this value gives 16,777,216 possible VNIs. This large address space is a primary advantage of VXLAN over traditional VLANs, enabling massive scalability required in modern multi-tenant data centers and cloud environments.

Question 3

What is the name of the Arista EOS feature that allows you to set triggers and perform actions on those triggers?

Accepted Answer

A

Explanation: Arista EOS Event Manager is a powerful on-box automation feature that allows network administrators to create event handlers. These handlers are composed of two main parts: a trigger and an action. A trigger defines the specific system event or condition to monitor, such as an interface state change, a syslog message pattern, or a scheduled time. When the trigger condition is met, the handler executes a predefined action, which can be a sequence of CLI commands, a shell command, or the execution of a custom script. This enables proactive, automated responses to network events directly on the switch.

Question 4

What is required in order for Multi-Switch CLI to be implemented?

Accepted Answer

B

Explanation: Arista's Multi-Switch CLI feature leverages the Extensible Messaging and Presence Protocol (XMPP) to enable a single command-line interface to manage a group of switches. This architecture requires a central XMPP server, also known as a broker, to facilitate communication. The Arista switches act as XMPP clients that connect to this server and join a multi-user chat room. Without the XMPP server, there is no central point for the switches to connect to, and the feature cannot be implemented. EJabberd is a commonly used open-source XMPP server suitable for this purpose.

Question 5

Which of the following best describes Arista’s MLAG feature?

Accepted Answer

A

Explanation: Arista's Multi-Chassis Link Aggregation (MLAG) allows two physical switches to appear as a single logical switch to a connected device. This enables the creation of a standard Link Aggregation Group (LAG) with member ports spread across the two MLAG peer switches. The primary benefit of this architecture is that both uplinks in the LAG can be active and forward traffic simultaneously. This active-active forwarding model eliminates the need for Spanning Tree Protocol (STP) to block one of the redundant links to prevent loops, thereby utilizing the available uplink bandwidth much more efficiently and providing superior resiliency.

Question 6

Which of the following statements are true?

Accepted Answer

B

Explanation: VMTracer's Adaptive Segmentation feature is a function that operates on the local Arista switch where it is configured. It integrates with a virtualization manager, such as VMware vCenter, to discover which VLANs are actively being used by virtual machines on a connected ESXi host. The switch then dynamically modifies the allowed VLAN list on its own trunk port(s) that connect to that specific ESXi host. This ensures that only necessary VLANs are trunked to the hypervisor, pruning unused ones to prevent unnecessary broadcast and multicast traffic from being forwarded to the host. The scope of this automation is local to the switch and its direct connection to the hypervisor.

Question 7

Which command would you use to change the SSH Idle timeout after entering the ‘management ssh’ command?

Accepted Answer

A

Explanation: Within the Arista EOS command-line interface, configuration of the SSH server is performed under the management ssh context. To modify the period an SSH session can remain inactive before being automatically disconnected, the idle-timeout command is used. This command accepts a value in minutes (from 0 to 1440), where a value of 0 disables the timeout. This is a security feature to prevent idle, authenticated sessions from remaining open indefinitely, reducing the risk of unauthorized access.

Question 8

To upgrade the EOS running on an Arista switch, which of the following commands copies the new EOS file from USB to flash?

Accepted Answer

A

Explanation: The correct command to copy a file from a USB drive to the internal flash memory on an Arista switch is copy usb1:/ flash:/ . In Arista's Extensible Operating System (EOS), physical storage devices are accessed using specific prefixes. The internal flash memory is designated as flash:, and the first USB port is identified as usb1:. The command structure follows the copy format, making option A the syntactically and functionally correct choice for this operation.

Question 9

True or False: When ZTP has been placed in cancel mode, you must issue the write memory command to prevent ZTP from triggering again.

Accepted Answer

False

Explanation: 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.

Question 10

Which of the following are valid Event Manager triggers?

Accepted Answer

A, C

Explanation: Arista's Event Manager allows automated actions based on specific system events. An event handler script is initiated by a defined trigger. The on-boot trigger executes the handler after the switch boots and the startup configuration is applied. The on-startup-config trigger executes the handler whenever a write memory or copy running-config startup-config command is issued, indicating a change to the startup configuration. These are both explicitly documented and valid trigger conditions within Arista EOS for event handlers.

Question 11

On EOS 4.15 and above, the ability to show JSON output for EOS CLI commands is available. Which of the following will successfully produce JSON output for the show version command?

Accepted Answer

B

Explanation: On Arista EOS version 4.15 and later, the standard method to format the output of a show command into JSON is by appending a pipe (|) followed by the json keyword. The pipe redirects the standard, human-readable output of the show version command to an internal EOS process that converts it into a structured JSON format. This feature is designed to facilitate automation and programmatic interaction with the switch's state information via the Command Line Interface (CLI).

Question 12

What is the packet overhead for a VXLAN-encapsulated frame?

Accepted Answer

C

Explanation: 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.

Question 13

Many Arista switches support reversible air flow. When the fans installed on such a switch have red handles, which of the following statements would be correct?

Accepted Answer

D

Explanation: Arista uses color-coding on its fan and power supply modules to indicate the direction of airflow, but this coding has not been consistent across all hardware platforms. On several switch series, such as the 7150S and 7280R3, red handles or markings signify a forward airflow pattern. This is also known as front-to-rear or port-side intake airflow. In this configuration, the switch draws cool air in from the port side (front) and exhausts the heated air out through the fan side (rear). Therefore, with red-handled fans on these specific platforms, hot air is ejected from the fan side of the switch.

Question 14

True or False: When configured as an MLAG domain, the Arista switches use the same MLAG System ID.

Accepted Answer

True

Explanation: The fundamental principle of Multi-Chassis Link Aggregation (MLAG) is to make two separate physical switches appear as a single logical switch to a connected device. To achieve this, both switches in the MLAG domain must present a unified identity during LACP (Link Aggregation Control Protocol) negotiations. They do this by sharing a common MLAG System ID, which is a unique MAC address configured to be identical on both MLAG peers. This shared System ID ensures that any downstream device sees a single LACP partner, allowing it to form a port-channel across the two physically distinct Arista switches.

Question 15

On an Arista 7150-24, which of the following commands would successfully help you to determine which ports would be subsumed within Ethernet1 configured at 40Gbps?

Accepted Answer

A

Explanation: The Arista 7150 series switches are built on the Fulcrum Microsystems FM6000 (Alta) ASIC. These switches feature "agile ports," where four 10GbE SFP+ ports can be logically combined to function as a single 40GbE QSFP+ port. To determine the current mapping and see which physical 10GbE ports are subsumed by a logical 40GbE interface, the correct command is show platform fm6000 agile-port map. This command is a platform-specific verification command and is executed from the privileged EXEC mode (#), not a configuration mode.

Free Arista ACE-A1.2 Actual Exam Questions