I need to prove that the encryption settings we have in our app\'s connection string are working.
What would be the simplest way to validate that traffic from our web
I would set the Force Protocol Encryption to true and Trust Server Certificate to true in the db connection string. The server should fail to establish a connection if it cannot provide you with an encrypted connection as requested. There is an article that covers encryption with sql server 2005 and later.
Simple test is to try a connection with and without encryption and fail when it hands out the undesired type of connection. then its up to the DBA, IT or you to configure the server to match your requirements.