Which host_regex expression will capture all logs pertaining to iis_vmail1, iis_vmail2, and iis_vmail3?

The correct answer provides a regex pattern that effectively captures the specific naming format of the logs in question. The expression combines elements to match any sequence of word characters followed by "vmail" and then any sequence of characters until it encounters the ".log" extension. The pattern starts with "\w+", which matches a series of word characters (letters, digits, or underscores) before capturing "vmail" with the subsequent characters.

This structure allows for flexibility, as it will successfully match "iis_vmail1", "iis_vmail2", and "iis_vmail3", while also accommodating any other potential prefixes as long as they fit within the \w+ character class. The use of the ".log" suffix ensures that only log file names are considered.

The other choices lack the necessary components to capture all log files related to the specified hosts. For instance, the second option does not include the prefix, thereby omitting the initial "iis_" part. The third option is specifically looking for a path structure, which may not generalize to the names in question. Lastly, the fourth choice would capture "iis_vmail" followed by a digit, but does not account for any preceding characters, limiting its ability to generalize for other potential prefixes