Arista : 2022 Notice and Proxy Statement - 2021 Annual Report

April 20, 2022

2021 Milestones:

• • Revenue for our fiscal year 2021 was $2.95 billion, an increase of 27.2% compared to fiscal year 2020.

• • Arista expanded the Arista EOS® network stack with the introduction of Network Data Lake (NetDLTM) for data-driven cloud networking, endorsed by Equinix, Palo Alto Networks, Red Hat, Slack, Splunk, VMware, and Zscaler.

• • Arista introduced a new zero trust security framework, Multi-Domain Macro-Segmentation Service, a suite of capabilities for integrating security policy with the network through open and consistent network segmentation.

• • Arista expanded its Cognitive Campus with the latest generation Wi-Fi 6E solution to meet enterprise IoT and collaborative applications requirements.

• • Arista expanded 400G for enterprise and cloud customers with the next generation of the 7050X and 7060X Series, providing performance and cost benefits for customers of all sizes as they transition to 400G networks.

• • KuppingerCole has recognized Arista NDR as a leader in the 2021 Leadership Compass for Network Detection and Response (NDR).

As we enter the next era of data-driven cloud networking, Arista is well positioned to continue its track record of relentless innovation to bring highly differentiated products to market.

I thank Arista stockholders, customers, partners and our employees for your continued support.

JAYSHREE ULLAL

Chief Executive Officer, President and Director Arista Networks, Inc.

The Arista family has shown great resilience and flexibility in the last year, maintaining operational excellence in the face of industry-wide challenges to establish Arista among the fastest growing networking companies in this decade.

I am delighted with Arista's record 2021 milestones in innovation, diversified customer momentum, and earnings. Our customer base now exceeds 8000, as we experienced continued strength in our cloud and enterprise business, including growing our campus revenues 100% year over year. Customer demand remains strong for Arista products as we are gaining market share in 100G, 200G and 400G high performance switching according to market analysts.

JAYSHREE ULLAL

Chief Executive Officer, President and Director Arista Networks, Inc.

[THIS PAGE INTENTIONALLY LEFT BLANK]

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

To Be Held at 11:00 a.m. Pacific Time on Tuesday, May 31, 2022

Dear Stockholders of Arista Networks, Inc.:

The 2022 annual meeting of stockholders of Arista Networks, Inc. (the "Company"), a Delaware corporation, and any postponements, adjournments or continuations thereof (the "Annual Meeting"), will be held on Tuesday, May 31, 2022 at 11:00 a.m. Pacific Time. Due to the COVID-19 pandemic and related public health concerns, the Annual Meeting will be conducted in a virtual format to provide a safe experience for our stockholders and employees. You will be able to attend the Annual Meeting online and submit your questions during the meeting atwww.virtualshareholdermeeting.com/ANET2022. To access the virtual meeting, you will need to enter the control number included in your Notice of Internet Availability of Proxy Materials (the "Notice"), on your proxy card or on the instructions that accompanied your proxy materials.

Our board of directors has fixed the close of business on April 6, 2022 as the record date for the Annual Meeting. Only stockholders of record on April 6, 2022 are entitled to notice of and to vote at the Annual Meeting. Further information regarding voting rights and the matters to be voted upon is presented in the accompanying proxy statement. If you plan on attending this year's annual meeting as a stockholder, you must follow the instructions set forth on page 61 of the accompanying proxy statement.

On or about April 20, 2022, we expect to mail to our stockholders the Notice, which provides instructions on how to access our proxy statement for the Annual Meeting and our annual report to stockholders, how to vote online or by telephone, and how to receive a paper copy of the proxy materials by mail. The accompanying proxy statement and our annual report can be accessed directly at the following Internet address:www.proxyvote.com. All you have to do is enter the control number located on your proxy card.

YOUR VOTE IS IMPORTANT. We urge you to submit your vote via the Internet, telephone or mail.

We appreciate your continued support of Arista Networks, Inc. and look forward to either greeting you virtually at the Annual Meeting or receiving your proxy.

By order of the Board of Directors,

JAYSHREE ULLAL

Chief Executive Officer, President and Director

Santa Clara, California

April 20, 2022