Search domain to match any occurrence on string

Hi guys!

I still could not understand why while searching in the graylog a specific domain, it cannot match the subdomain address containing the domain searched…

Am I searching it wrong or this way of searching would simply not work?

Below are the tests that I’ve made so far…

Success (with subdomain)

Failure (without subdomain)

Failure (regex without subdomain)

External Regex Test