Lots of contradictory on these subjects and I don't know why.

My first question is about the 64 bit WWN. One reference claims the terms WWN and WWPN are synonymous. An online source seems to refute this. They say:

A WWPN (world wide port name) is the unique identifier for a fibre channel port where a WWN (world wide name) the unique identifier for the node itself. A good example is a dual port HBA. There will be two WWPN's (one for each port) and only a single WWN for the card itself.

Question #1: Which is correct? I’m almost positive I read that every “Port” has a WWN.

My next question is about the 24 bit FC address that is dynamically allocated to a port when it is introduced to the switch. The Domain ID field is defined as: "a unique number provided to each switch in the fabric."

Question #2: Do Domain IDs only apply to switch ports? For example what would the Domain ID be for a HBA? None? The same as the switch port it is connected to?

Question #3: My last question is about the Name Server of a switch. A book example shows the routing of a message through the switch. It uses the WWNs of the source and destination ports to route the message. I am assuming that the Name Server must associate the WWN and the FC address in some way in order to route the message, correct?