Where does the vent pipe connect to a bathroom sink drain?

In the wall within 5 feet if it is 1 1/2" and 8 feet if 2" pipe. Some are not vented if it is 2" and some have a studor vent exposed under the cabinet.

Correction Doug, My code book makes it 3 1/2' for 1 1/2" and 5' for a 2" drain line.