Exam MS-721 topic 1 question 129 discussion

None of the options in the dropdown are correct. A "?" before a digit implies the preceding digit can match 0 or more occurrences of that token. If the input is any 7 digits preceded with 8 or without 8, the regex will match. The translation +1330 is added at the beginning for every pattern that matches the regex, resulting in a complete E.164 format. ############################## PowerShell Test: ############################## PS C:\Users\PsScripts> ("85551212" -match "^8?(\d{7})$") True PS C:\Users\PsScripts> ("5551212" -match "^8?(\d{7})$") True ############################## The answer for both should be +13305551212 (CC-NPA-NXX-<4 digit extension>)

I believe the answer is +13305551212 in both instances. ? means match what's before the ? zero or more times. The $1 means reuse what is inside of the (), which is 7 digits.