Arista ACE-A: Certified Engineering Associate Interview Questions

To pass the interview phase and become an Arista ACE-A: Certified Engineering Associate, expertise in the Arista switch and its command-line interface is required. Moreover, you must be able to demonstrate your expertise in configuring the Arista EOS CLI and use API commands and features that utilize XMPP. Additionally, you can also go through the Arista ACE-A online tutorial to get a grasp of the important resources for exam preparation to enhance your skills and confidence. Our Free Practice Tests will further enhance your answer writing skills to help pass the exam in one go!

Once you have accepted a job offer and have set an interview date, it’s natural to be nervous. While this is expected, it’s important to remember that the interviewer isn’t out to get you. Chances are, the employer wants you to succeed in their organization and will ask the types of questions listed below to determine if you’re a good fit for the position. So let’s have a look at the list of top Arista ACE-A Interview Questions!

Advanced Interview Questions

What is your experience with Arista networks and the EOS operating system?

As a Certified Engineering Associate with Arista networks and the EOS operating system, I have had a truly exciting and challenging experience. The EOS operating system is a cutting-edge technology that has been designed to meet the needs of modern data center networks. Working with this technology has allowed me to gain a deep understanding of the latest networking technologies and how they are used to build large-scale, highly scalable, and highly available networks.

I have been fortunate to work on various projects using the EOS operating system, including designing, implementing, and maintaining large-scale data center networks. The EOS operating system has a user-friendly interface, which makes it easy for me to navigate and configure the network. The platform also has a wealth of features that allow me to manage, monitor, and troubleshoot the network with ease.

In addition to my work with the EOS operating system, I have also had the opportunity to work with some of the brightest minds in the industry. This has allowed me to expand my knowledge and skills, and has given me the opportunity to contribute to the growth and success of the company.

Overall, my experience as a Certified Engineering Associate with Arista networks and the EOS operating system has been an incredibly enriching one. I have had the opportunity to work with some of the best technologies in the industry, and have been able to gain a wealth of knowledge and experience that I will carry with me for the rest of my career.

Can you explain the concept of VLANs and VLAN tagging in Arista networks?

VLANs, or Virtual LANs, are a way to segment a network into smaller, more manageable sub-networks. VLANs are used to create separate logical networks within a single physical network, and each VLAN is essentially its own independent network.

VLANs are typically used to segment a network based on certain criteria, such as department, location, or security level. For example, you could create a VLAN for the finance department, a VLAN for the sales department, and a VLAN for guest wireless access. Each VLAN would be isolated from the others, meaning that devices within one VLAN would not be able to communicate directly with devices in another VLAN.

VLAN tagging is the process of adding a VLAN tag, or identifier, to a packet as it traverses a network. This tag is used to identify the VLAN to which the packet belongs, and it enables the switch to forward the packet to the appropriate port or VLAN. VLAN tagging is typically done using the IEEE 802.1Q standard, which defines a 4-byte tag that is inserted into the Ethernet header of a packet.

In Arista networks, VLANs are configured using the “vlan” command in the EOS CLI. The command creates a new VLAN with a specified ID and assigns it a name. Once a VLAN is created, ports on the switch can be assigned to it using the “switchport access vlan” command. The switchport command assigns a VLAN to a port in access mode, meaning that all frames received on that port are associated with that VLAN and all frames transmitted on that port are tagged with the VLAN ID.

In addition, VLAN tagging can be enabled on a port-by-port basis using the “switchport mode trunk” command. This command puts the port into trunk mode, which allows the port to carry multiple VLANs at the same time. Trunk ports are typically used to connect switches together, or to connect a switch to a router. When VLAN tagging is enabled on a trunk port, the switch will insert a VLAN tag into the Ethernet header of all packets passing through the port. This allows the switch to identify the VLAN to which a packet belongs, even when the packet is traversing multiple switches.

It is worth noting that Arista switches also support private VLANs (PVLAN) which allows to segment a VLAN into multiple isolated sub-VLANs, known as Secondary VLANs, or PVLANs. These PVLANs can communicate with the primary VLAN or with each other but not with other PVLANs in the same VLAN.

How would you troubleshoot a network connectivity issue on an Arista switch?

I would start by logging into the switch and checking the basic connectivity. I would run the command “show interfaces” to check the physical state of each port and verify if any port is down. If any port is down, I would check the cabling and ensure that it’s properly connected and functional.

Next, I would run the command “show ip interfaces brief” to check the IP configuration of each interface and verify that they have the correct IP address, subnet mask, and gateway. I would also verify that the switch is able to ping other devices on the network.

If the issue still persists, I would check the switch’s routing table by running the command “show ip route”. I would verify that the switch has the correct routing information and is able to reach the default gateway.

If the switch is still unable to connect to other devices on the network, I would check the switch’s firewall rules. I would run the command “show firewall” to check the firewall configuration and ensure that there are no rules blocking traffic from the switch.

Finally, I would check the switch’s logs to see if there are any error messages or warnings that might provide further information about the connectivity issue. I would run the command “show logging” to access the logs.

If all of these steps fail to resolve the issue, I would seek assistance from Arista’s technical support team for further troubleshooting.

How do you configure sFlow on an Arista switch?

sFlow is a standard protocol for monitoring network traffic and collecting statistics. It allows network administrators to monitor the performance and usage of their network devices and links in real-time.

To configure sFlow on an Arista switch, you need to follow these steps:

1. Enable the sFlow feature on the switch by running the command “sflow” in the switch’s config mode.
2. Configure the sampling rate. This is the rate at which packets are sampled and sent to the sFlow collector. You can do this by running the command “sampling <rate>”, where “rate” is the number of packets to be sampled out of every 1,000 packets. For example, to sample 1 out of every 100 packets, the command would be “sampling 10”.
3. Configure the polling interval. This is the time interval at which the switch sends sFlow samples to the collector. You can do this by running the command “polling-interval <interval>”, where “interval” is the time interval in seconds. For example, to send samples every 30 seconds, the command would be “polling-interval 30”.
4. Configure the sFlow collector. You need to specify the IP address and port number of the sFlow collector to which the switch will send the samples. You can do this by running the command “collector <ip-address> <port-number>”. For example, “collector 192.168.1.1 6343”
5. Configure the target ports. You need to specify which ports on the switch should be monitored by sFlow. You can do this by running the command “target <port-list>”, where “port-list” is a list of ports separated by commas. For example, “target Ethernet1, Ethernet2, Ethernet3”
6. Configure the target VLANs. You can also specify which VLANs on the switch should be monitored by sFlow. You can do this by running the command “target vlans <vlan-list>”, where “vlan-list” is a list of VLANs separated by commas. For example, “target vlans 10, 20, 30”
7. Save the configuration by running the command “write memory”

Once the configuration is saved and applied, the switch will begin sending sFlow samples to the specified collector at the specified intervals. The collector can then use this data to generate network usage and performance statistics.

It is important to note that, before configuring sFlow, it is recommended to understand the network topology and the traffic pattern to properly set the sampling rate and polling interval, otherwise, it may lead to high CPU consumption and storage overheads.

Can you explain the use of the ‘spanning-tree’ command in Arista EOS?

The spanning-tree command in Arista EOS is used to configure the Spanning Tree Protocol (STP) on a switch. STP is a layer 2 protocol that is used to prevent loops in a network by selecting a single active path between two endpoints and blocking all other paths. This is done by creating a tree-like structure where one switch is designated as the root and all other switches in the network determine their position in the tree based on the root.

The spanning-tree command is used to configure various parameters of the STP, such as the STP mode, the root bridge, and the STP priority.

When configuring STP, you can specify the mode of operation, which can be either “MSTP” (Multiple Spanning Tree Protocol) or “RSTP” (Rapid Spanning Tree Protocol). MSTP is the default mode in Arista EOS and allows you to create multiple spanning tree instances on a single switch. RSTP is an evolution of STP that provides faster convergence in case of a topology change.

Additionally, the root bridge can be configured with the “spanning-tree root” command. The root bridge is the switch that is at the top of the spanning tree and all other switches in the network determine their position in the tree based on the root bridge.

The “spanning-tree priority” command is used to configure the priority of a switch for the root bridge election. The switch with the lowest priority will be chosen as the root bridge.

In summary, the spanning-tree command in Arista EOS is used to configure the Spanning Tree Protocol, which is a layer 2 protocol that prevents loops in a network by selecting a single active path and blocking all other paths. The command can be used to set different modes, configure the root bridge and set the priority of a switch in the network.

What is the difference between ‘switchport mode access’ and ‘switchport mode trunk’ in Arista EOS?

As a network engineer using Arista EOS, I understand that ‘switchport mode access’ and ‘switchport mode trunk’ are two different modes for configuring the switchports on my network.

When I configure a switchport in ‘switchport mode access’, I am effectively making it a single VLAN port. This means that the switchport will only be able to communicate with other devices on the same VLAN. This mode is typically used for end-user devices such as workstations, laptops, and printers.

On the other hand, when I configure a switchport in ‘switchport mode trunk’, I am allowing it to carry multiple VLANs, enabling communication between different VLANs. This mode is used when connecting to other switches or routers.

In summary, ‘switchport mode access’ is used for single VLAN connections, while ‘switchport mode trunk’ is used for multi-VLAN connections.

How would you configure link aggregation (LAG) on an Arista switch?

Link aggregation, also known as NIC teaming or NIC bonding, is a method of combining multiple network interfaces (NICs) into a single logical interface. This can provide several benefits, such as increased bandwidth, redundancy, and load balancing. On Arista switches, link aggregation is achieved using the Link Aggregation Control Protocol (LACP) and the Link Aggregation Bundle (LAG) interface.

To configure link aggregation on an Arista switch, you would typically use the following steps:

1. Create a LAG interface: This is done using the “interface lag <lag-id>” command. The <lag-id> is an integer value that identifies the LAG interface. For example, “interface lag 1” would create a LAG interface with ID 1.
2. Add physical interfaces to the LAG: This is done using the “member <interface-name>” command within the LAG interface configuration. For example, “member ethernet 1/1” would add Ethernet interface 1/1 to LAG 1.
3. Configure LACP: This is done using the “lacp” command within the LAG interface configuration. LACP is a standard protocol for managing link aggregation and provides dynamic negotiation of bundle parameters. You can also configure the mode of LACP as active/passive, which will control the way switches initiate LACP negotiation.
4. Configure the LAG protocol: This is done using the “lacp rate” command within the LAG interface configuration. This command sets the rate at which LACP packets are sent. The options are “slow” or “fast”, with “slow” being the default.
5. Apply the LAG to a VLAN: This is done using the “switchport trunk allowed vlan <vlan-id>” command within the LAG interface configuration. This command allows the specified VLAN to be carried over the LAG bundle.
6. Verify the LAG configuration: This can be done using the “show lacp” command, which will show the LAG bundle status, including the member interfaces, LACP status, and LAG protocol rate.

It’s worth noting that LAG is supported on both Layer 2 and Layer 3 interfaces, and LAG interfaces can be configured with IP addresses and can be used for routing as well. Additionally, LAG can be used for both static and dynamic LAGs, and it is also important to monitor the LAGs for any issues or errors.

Can you describe the process for upgrading the EOS software on an Arista switch?

To upgrade the EOS software on an Arista switch, I would follow the following steps:

1. Download the latest version of the EOS software from the Arista website.
2. Copy the software to the switch’s bootflash. This can be done through a secure copy (SCP) protocol.
3. Verify the new software version on the switch by using the command “show version”.
4. Take a backup of the current configuration of the switch, in case of any issues during the upgrade process.
5. Enter the command “copy bootflash:<filename> flash:” to upgrade the switch software.
6. After the upgrade is complete, restart the switch by using the command “reload”.
7. Once the switch has restarted, log in and verify that the new software version has been installed and is running correctly.

It’s important to follow the steps carefully and to verify the software version before and after the upgrade to ensure that the process was successful and the switch is operating correctly.

How do you configure VXLAN on an Arista switch?

To configure VXLAN on an Arista switch, I would follow these steps:

1. First, I would make sure that the switch software is updated to the latest version that supports VXLAN.
2. Next, I would create a VLAN interface to be used as the VXLAN network identifier (VNI) using the command “interface vlan <VLAN_ID>”.
3. After that, I would enable VXLAN on the VLAN interface by entering the command “ip virtual-router mac-address <MAC_ADDRESS>” followed by the command “vxlan source-interface <INTERFACE_NAME>”.
4. Then, I would configure the VXLAN IP address using the command “ip address <IP_ADDRESS>/<NETMASK>”.
5. I would then create a VXLAN tunnel interface using the command “interface vxlan1”.
6. I would then specify the VNI for the VXLAN tunnel interface using the command “vxlan vni <VNI_ID>”.
7. To configure the remote endpoint, I would enter the command “vxlan udp-port 4789” followed by the command “vxlan flood vtep <REMOTE_ENDPOINT_IP_ADDRESS>”.
8. I would then configure the VLAN to VXLAN mapping using the command “vxlan vlan <VLAN_ID> vni <VNI_ID>”.
9. Finally, I would verify my configuration using the command “show interfaces vxlan1” and “show vxlan vni”.

By following these steps, I should have successfully configured VXLAN on my Arista switch.

Can you explain the concept of virtual routing and forwarding (VRF) in Arista EOS?

Virtual Routing and Forwarding (VRF) is a technology used in computer networks to isolate different routes for different users or applications. In Arista EOS, VRF allows multiple routing tables to coexist within the same router at the same time, each with its own set of routes and interfaces. This allows for the creation of separate and independent routing domains within a single device, which can be useful in scenarios where different departments or customers need to have their own routing and addressing schemes, but share the same physical infrastructure.

When a VRF is configured on an Arista switch, it creates a separate, independent routing table for that VRF. Each VRF can have its own set of interfaces, routes, and protocols. For example, you can configure OSPF or BGP for each VRF independently, allowing for different routing protocols to be used for different VRFs.

VRF also allows for the use of unique IP addresses for different VRFs on the same physical interface. This is achieved by using a technique called “VRF-Lite” which uses the same IP address on different interfaces, but assigns them to different VRFs. This allows for the creation of virtual interfaces that are unique to each VRF.

VRF also allows for security measures such as route leaking, which allows for the exchange of routes between different VRFs. This is useful when you want to share routes between different VRFs while still keeping them isolated.

In summary, VRF in Arista EOS allows multiple routing tables to coexist within the same router, each with its own set of routes and interfaces, creating separate and independent routing domains within a single device. This allows for the creation of unique routing and addressing schemes for different departments or customers, while still sharing the same physical infrastructure.

Basic Interview Questions

1. What is the basic switch configuration?

 The basic switch configuration involves the minimum network, port, and security provisioning for production deployment. However, your exact needs will vary from environment to environment, and effective switch management is a detailed topic in its own right.

2. What are the five steps in a switch boot sequence?

• The Startup. 
• BIOS: Power On Self Test.
• Loading of OS
• System Configuration
• Loading System Utilities
• User Authentication.

3. Could you tell me something about the management port in a switch?

 By using a management port, a network administrator can manage and configure network devices remotely. A console port is used in conjunction with a console server to create a separate dedicated network that allows administrators to access devices on the primary network in case the primary network goes down.

4. What is the difference between a console port and a management port?

 The console port is for serial management. Usually, you directly connect it to your laptop. The management port is used for out-of-band network management of the switch.

5.  Could you explain what you need Ethernet ports for?

 Ethernet cables are most commonly used to connect a WiFi router or modem to the internet entry port or telephone line. They plug into Ethernet ports on a variety of devices. When you want to connect a WiFi router or modem to the internet entry port or telephone line, using the Ethernet cable is the best approach.

6. Is Ethernet faster than Wi-Fi?

 To access a network via an Ethernet connection, you need to connect your device with an ethernet cable. An Ethernet connection is generally faster than a WiFi connection, which provides greater speed but less security than wired networks.

7. How would you set an environment command?

Setting an environment variable can be accomplished by using the command ” export varname=value “, which sets the variable and exports it to the global environment. If it contains spaces, then you must enclose the value within double quotes. For setting a local variable, you can use the command ” varname =value ” (or ” set varname =value “).

8. What is a zero-touch provisioning ZTP process?

Zero-touch provisioning (ZTP) helps IT teams quickly deploy network devices in a large-scale environment. ZTP automatically configures the device using a switch feature, eliminating most of the manual labor involved with adding them to a network.

9. Could you tell me the tasks automated in zero touch provisioning?

• updating firmware
• configuring devices or adding crucial features
• It does it all with no human intervention. 

Zero-touch provisioning can save you time, reduce costs, and reduce labor costs, among other things.

10. How would you describe one-touch provisioning?

Intel vPro devices can communicate with a provisioning server on the network, which listens for messages from Intel vPro devices and enables IT staff to manage servers regardless of the state of their OS.

11. What is SD Wan zero-touch provisioning?

When you consider that many SD-WAN implementations depend on Zero-Touch Provisioning (ZTP), which allows a remote technician to provision a router anywhere in the WAN, you can see how it lowers IT costs and increases network control. But only if it is designed and delivered as a secure, truly zero-touch solution.

12. What is a zero-touch deployment?

 Zero Touch Deployment, a feature that automatically registers and distributes X. 509 certificates and provisioning information over secure connections within a connected grid network, makes the process of deploying new devices easy and fast.

13. What is the command-line interface of a data switch? 

 The command-line interface is the primary tool for configuring and managing network devices such as routers or Ethernet switches. Using the CLI, you can type in configuration commands that produce output from the router or switch.

14. What are the common methods to access the CLI?

• Web Interface.
• Data Link.
• RxControl.
• PuTTY or any other terminal application.

15. Could you explain to me what is XMPP for?

 Extensible Messaging and Presence Protocol (XMPP) is a proven, open XML technology used for real-time communication in a wide range of applications that include instant messaging, presence, and even collaboration.

16. How does multi-chassis LAG work?

 Multi-chassis link aggregation groups can allow a client device to form a logical link aggregation interface between two multi-chassis link aggregation group peers. This can provide redundancy and load balancing between the two multi-chassis link aggregation group peers, multihoming support, and a loop-free Layer 2 network without Spanning Tree Protocol.

17. Why do you need MLAG?

MLAG takes the benefits of link aggregation and spreads them across a pair of data center switches to deliver system-level redundancy and network-level resiliency. Arista’s MLAG feature allows you to scale at Layer 2 without wasting bandwidth in Spanning Tree Blocked mode.

18. What is the difference between lag and MLAG?

 Arista’s MLAG feature increases availability by enabling pairwise link aggregation across switches, creating a redundant system of bandwidth without the bandwidth waste of spanning-tree blocking.

19. Could you differentiate between MLAG and stacking?

 MLAG allows for greater bandwidth as the number of network users increases, and in many cases can increase bandwidth without having to upgrade your network hardware.

20. How is MLAG different from vPC?

 MLAG is an open standard that most vendors can support, whereas vPC is a protocol specific to Cisco Nexus switches. Thus, MLAG configurations are easier than those for vPC.

21. Can you explain to me what is EOS for?

 EOS is a blockchain platform that aims to support commercial-scale decentralized applications. It provides secure access and authentication, permissions, data hosting, usage management, and communication between dApps and the Internet.

22. What is the use of EOS in Arista?

 Arista EOS is the core of Arista cloud networking solutions for next-generation data centers and cloud networks. Designed to scale to hundreds of thousands of compute and storage nodes, Arista EOS enables cloud architectures with management and provisioning capabilities that work at scale.

23. How would you describe Aboot in Arista?

 Aboot is an Arista switch’s boot loader. In addition to loading the switch’s operating system (EOS), Aboot can be used to change boot parameters, restore default switch settings, diagnose hardware failures and manage switch files. Aboot Shell describes the Aboot shell.

24. What is meant by the term VXLAN?

VM Tracer is a VMware switch feature that discovers the networks configured on VMware host servers. The switch uses VMware’s SOAP XML API to find virtual machines and their network configurations (VLANs and distributed/virtual switches).

25. How would you define VM Tracer?

 VM Tracer is a feature that uses VMware’s SOAP XML API to discover VMware host server components. The switch determines the network configuration and requirements of connected VMware hypervisors by discovering instantiated VMs with their network configuration (VLANs and distributed/virtual Switches).

26. What is Arista tap aggregation?

 Arista’s TAP aggregation capabilities give you network and application performance and security visibility. You can build networks that are an order of magnitude less expensive than what has been possible previously.

27. Could you elaborate on the purpose of Agile Ports?

 An agile port is an interface that can function as a 10G port or subsume a predefined set of 10G interfaces to form an interface with higher speed capabilities. The set of interfaces that can be combined depends on the hardware configuration.

28. What do you know about advanced monitoring?

 Monitoring agents are software programs that track the activity on workstations and servers via continuous, 24/7 scanning. They help IT support staff keep computers secure from malicious software and help them spot potential problems before they become major issues.

29. How would you explain the use of Arista e-API?

In addition to the EOS API, Arista’s newest platform, EOS API (e-API), also enables scripts and applications to access all aspects of EOS programmatically.

30. What is meant by the term CLI in API?

 A command-line interface (CLI) is a user interface (UI) that allows users to interact with their computers. It uses text and commands to display information and carry out tasks on the computer. Command-line interfaces are also named console user interfaces, command-line user interfaces, and character user interfaces.