In web application level we can set anonymous access in SharePoint.
Web Application Level
When we create Web Application in SharePoint you can set the anonymous access at the web application level. It will allow the entire anonymous user to access the site.
--> Go to SharePoint Central Administration site select “Application Management” -> “Manage web application"
-->Create "New" web application
-->Choose “Yes” for “Allow Anonymous”
Already existing site we have to set anonymous, we have to do two steps
Go to SharePoint Central Administration site select “Application Management” -> “Web Application Management”
--> In Web Application Management screen select the particular web application in ribbon click on Authentication providers.
--> In authentication Provider select the zone in which you need to change the authentication.