It's the PTR record (reverse DNS) corresponding to the IP which your computer was assigned via DHCP.
It changes each time your computer gets a new address from DHCP and you can't make it static. The problem here is not in the settings on your computer, but on all the other computers connected to the campus network (i.e. computers try to connect to your computer). These machines ask DNS server for the IP address of [email protected] and DNS server gives them the corresponding IP address.
You'd need to make a DHCP reservation to get the same IP address always, but this only administrators can do.
You can check it with command-line:
dig -x <your_ip_address>
or if you know your interface name (here en0) automatically:
dig -x `ipconfig getifaddr en0`