That depends on how you route your internet connection. In most cases, you'll just route addresses from the client's network (typically in a subnet of 10.0.0.0/8).
route in a console to see your routing table. The first default entry determines how your regular internet connection flows. For example, the following configuration does route over the VPN:
0.0.0.0 172.16.0.5 0.0.0.0 tun0 # default via tun0(=VPN)
172.16.0.5 0.0.0.0 255.255.255.255 tun0
126.96.36.199 192.168.1.1 255.255.255.255 wlan0
192.168.1.0 0.0.0.0 255.255.255.0 wlan0
0.0.0.0 192.168.1.1 0.0.0.0 wlan0 # default via wlan0(local)
A simple alternative is checking whether your IP address changes when you connect to the VPN.