for a web application. Scroll down to the Authentication Records list. (If no records are defined for the web application, the list is empty.)Authentication to HTML forms is optional. These authentication techniques are supported: HTTP Basic server-based authentication and simple form authentication. One or more authentication records may be added to a web application to support authentication. Each record provides credentials (user name and password) to be used for authentication when the scan encounters a login form.
When authentication is enabled for a web application, the crawler attempts authentication the first time the web crawler encounters a login form. Upon success the crawler visits the form action link, gathers information for analysis and continues crawling.
Go to Account > Web Applications and click the edit icon for a web application. Scroll down to the Authentication Records list. (If no records are defined for the web application, the list is empty.)
Click the Add button to the right of the Authentication Records list and enter the authentication record settings and then click Save.
Click the edit icon , enter the authentication records settings and then click Save.
Click the delete icon 
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Tell me about the option "Send authentication over SSL only"