Accounts aren't needed in this context.
When you first try connecting to a fixed network, your computer doesn't have an IP address - it has no practical way of communicating on the network, just a very basic identifier called a MAC
address (which is hardwired into your PC
). So, it just hollers "somebody give me an IP address!" until it gets an answer.
Your network will have a DHCP server of some description, which is listening for this. It responds to your PC
with an offer of an IP address (the address is leased, for a limited time, but it gets renewed automatically if you stay online). The server has a pool of addresses that it can offer to PCs. It might offer one at random, or the network admin might have set up some particular rules for how they are allocated. They might even have told the DHCP server to reserve one address for each PC
, in which case you effectively get a fixed IP.
The DHCP server remembers who it leased the IP address to; so your network admin can find out at least your MAC
address. They can probably trace other details - port number, and/or hostname. You might be free to change the latter. If they offer anything more than basic network connectivity (IE they have a Windows domain, or whatever), this will will store more information that your network admins might use.
For the purposes of this post: Anything qualified with "can", "might", "probably", &c. is technically possible, but we can only guess as to whether or not it's actually done in that building.