The Global tab provides the global administration option settings for:
It is best to explicitly name the servers, rather than using regular expressions. For example, if your server naming convention is "$purpose-$operating_system-$letter$number$number$number.domain.com", you would specify "web-linux-A456\.domain\.com".
This option uses regular expressions to check whether the received HTTP_Referer field contains an allowed host, so if regular expressions are created improperly or are too permissive, it is possible that hosts could be allowed through that should not have access. If you wanted to allow ALL of your web servers to access your Watson Explorer Engine installation, you could use the following regular expression: "web-(linux|windows)-[a-z][0-9]{3}\.domain\.com". This means all servers with the name "web followed by a dash followed by either linux OR windows followed by a dash followed by ONE letter in the range A to Z followed by EXACTLY three numbers dot domain dot com". For more information on the proper syntax for expressions, see POSIX Regular Expression Syntax and Examples.