Which search string only returns events from host WWW3?

The choice that returns events specifically from the host WWW3 is the one that uses the exact syntax "host=WWW3". This search string precisely targets events associated with that particular host name. In Splunk, search queries are case-sensitive, and the exact matching of terms is crucial for retrieving specific data.

Using "host=WWW3" ensures that the search results are limited to entries that exclusively reference WWW3 without variations or partial matches. This is important in scenarios where hosts might have similar names or when it's necessary to filter out noise from other data sources effectively.

On the other hand, searching with "host=" would yield results from all hosts, which is too broad for the requirement of returning events from only WWW3. The option "host=WWW" would match any host name that starts with WWW, potentially returning results from various other hosts (like WWW1 or WWW2). Lastly, "Host=WWW3" would not work because the keyword must be case-sensitive and written as "host=WWW3" with a lowercase 'h'.