All of it.
the network portion of the destination ip address
The Destination Address (Layer 2 or Layer 3)
the router is assigned an ip address.
172.16.0.0
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network portion of ip address
The Router only has one M.A.C Address and One IP Address But, the Router can have many Connections ( Devices using the network ) That may shoe up as their IP Addresses. But the Router only Has One IP Address
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Your Router is assigned an IP address that is known as a public IP address then your router assigns out IP addresses that are known as local IP addresses. So the answer is yes and yes!
network portion of ip address
no a bridge does not use a IP address, it uses MAC address', rousters or layer 3 uses ip address.
If you have changed DHCP ip range, the ip address for your router has changed too. You can find your router ip address in your wireless adapter information.