Not quite. A phonebook would be static data (i.e. published only occasionally). WSD is live data - it would be more like an online directory than a phonebook. The printer advertises itself when it connects. The client (in this case the Microsoft WSDMon port monitor) validates the address each time that it connects so it is always correct.
In an enterprise environment where there are many printers then there can be a service that acts more like your live directory where it keeps track of the correct data and clients can ask it for the current address or other information.
The client does remember a unique ID value that the printer has and it can use that to ask the printer "what is your current address" each time that it needs it.
By the way, this is the advantage over the TCP/IP port monitor. It has static address data. If the printer gets a dynamic address from a domain name server then it will eventually change and break the TCP/IP connection. WSDMon will not break like that.
