# 3.3.1 Identifying Accounts

Accounts on Zoom can be optionally identified using a domain name, which we call the Account Domain Name (*ADN*). Domain names make good identifiers because they are unique (while for example two companies with the same name might exist in two countries), and many users are already familiar with them.

To set the *ADN*, an account administrator may choose one of the account’s Associated Domains. Associated Domains is a Zoom feature where an account admin can prove ownership of domain names (e.g. by adding a specific DNS record, adding a header tag to the home page, or hosting a file at a specific location on the domain) for the purposes of account and user management. Domain names consist of alphanumeric characters and hyphens.

Only a single account at a time can use a domain name as their *ADN*. Account administrators are allowed to change their *ADN* if needed. In the future, Zoom may provide a new dedicated subdomain as an option for accounts to use as the *ADN*.
