Getting some exceptions - what do they mean

Dear Usergroup,

I’m all new to Gatling and impressed of its abilities.

To evaluate a migration attempt I want to Stress-Test my migrated artifacts.
They only have two REST-Calls which I want to request 225 times a second.
For this I wrote a Scenario with:

constantUsersPerSec(225) during (10 minutes)

If I run it I got some different exceptions.
Can somebody tell what they mean in terms of Stress-Tests ?

- Connection timed out:
does it mean that my application was to slow to serve ?

- UnknownHostException:
is my network to slow ?

- UnknownHostException: temporary failure in name resolution
I have no idea

Hopefully I can get some answers from you.