Query on server names

Hi
When we do the sqoop import, we use nn01.itversity.com as part of the --connect parameter. Please let me know when we use gw01.itversity.com and what s the difference beween nn01 and gw01 servers.

Thanks
Subbu

gw01.itversity.com is a client which work as gateway node.
nn01.itversity.com have mysql running on it. By using connect we are connecting to databases running on mysql server.