What clause is used to group the output of a stats command by a specific name?

The correct answer is "By" because the "by" clause is an essential component of the stats command in Splunk. When using stats, this clause allows users to specify the field or fields that they want to group their aggregated results by. This grouping is fundamental for producing meaningful statistical outputs based on the specified criteria.

For example, if you want to calculate the total sales per region, you would include the "by" clause with the region field in your stats command. This tells Splunk to aggregate and display the results for each unique region, thus making it easier to analyze the data across those specified categories.

The other options relate to different functionality or are not part of the syntax for grouping in the stats command. The "as" clause is used to rename fields in your output, while "rex" is used for extracting fields using regular expressions. "List" is a function of the stats command but does not serve as a grouping clause; it is used to aggregate values into a multivalue field.