A naked domain (Bare domain) is simply a domain name without the 'www' prefix. For example, google.com (naked) instead of www.google.com (full)
Most websites map their naked domain to be forwarded to their www (full) address.
Cloud WAF offers a naked domain redirection to the 'www' site for all our customers. Go to the MY Console: https://my.imperva.com/admin/login?logout=true
Once logged in go to: Site >>> DELIVERY >>> Redirection.
For additional information, see also: Domain Redirection Feature.