Your other options are to use the console port with a serial cable (57,600, 8-N=1) which will give you a shell login on the server.
Or, ping the broadcast address on your network and then scan the ARP table for the server's MAC address.
If your machine is in the correct subnet you should be able to ping the last address - for example, if you use 192.168.1.x/255.255.255.0, the broadcast address will be 192.168.1.255.
Once you've pinged every machine in the network your machine will map its MAC address to its IP address which you can query via the
arp command. Specifically:
arp -a
will list every known IP/MAC address pair
Chances are, though, that you don't know the server's MAC address in which case you have two further options - first get a magnifying glass and look on the back of the server - the MAC address is printed in 4pt text on the label on the back. Alternatively, connect an ethernet cable directly between the server and your machine, wait 5 minutes (for the arp cache to expire) and ping the broadcast address. Then query the arp table and remove your own machine's entry (which you can find via
ifconfig -a - what's left should be the server.