= To match an alias from the cisco.com domain, with the host portion of the alias consisting of first name.1st name, with no limits on the length of either name, you need to use a regular expression that can capture any characters before and after a dot (.) and before the @ sign. A regular expression is a way of describing patterns of text using special characters and symbols1. The Expressway supports the use of regular expressions in several features, such as search rules, transforms, and dial plan2.
The regular expression that can match the desired alias is:
(.).(.)@cisco.com : This means that the Expressway will match any characters (.) zero or more times () before and after a dot (.) and before the @ sign, and capture them as two groups ((.)). The parentheses indicate the grouping of the characters. The dot is a special character in regular expressions that means any character, so it needs to be escaped with a backslash () to match it literally. The @ sign and the cisco.com are matched literally.
For example, this regular expression will match John.Doe@cisco.com, Jane.Smith@cisco.com, Bob123.Alice456@cisco.com, etc. and capture John, Doe, Jane, Smith, Bob123, and Alice456 as groups.
The other options are not correct because:
B. (\d*).(\d)@cisco.com : This means that the Expressway will match any digits (\d) zero or more times () before and after a dot (.) and before the @ sign, and capture them as two groups ((\d)). The parentheses indicate the grouping of the characters. The \d is a special character in regular expressions that means a digit from 0 to 9. This is too restrictive and will not match any characters other than digits, such as letters or symbols.
C. (.)/(.)@cisco.com : This means that the Expressway will match any characters (.) zero or more times () before and after a slash (/) and before the @ sign, and capture them as two groups ((.)). The parentheses indicate the grouping of the characters. The slash is not a special character in regular expressions, so it is matched literally. This is incorrect because the alias does not contain a slash, but a dot, between the first name and the last name.
D. (.).()@cisco.com : This means that the Expressway will match any characters (.) zero or more times () before and after a dot (.) and before the @ sign, and capture them as two groups ((.)). The parentheses indicate the grouping of the characters. The dot is a special character in regular expressions that means any character, so it is not escaped with a backslash () to match it literally. This is incorrect because the dot will match any character, not just a dot, between the first name and the last name.
References := Regular Expressions, Cisco Expressway Basic Configuration Deployment Guide
