The first and most simplest way to translate hostnames into IP-addresses is by using a table telling which IP-number belongs to which hostname(s). This table is stored in the file `/etc/hosts' and has the following format:
<IP-address> <hostname> [<nickname> [...]]
Lines starting with a hash mark ("#") are treated as comments. The other lines contain one IP-address and the corresponding hostname(s).
It's not possible for a hostname to belong to several IP-numbers, even if I made you think so when talking about routing. RZI for example has really two distinct names for each of its two addresses: RZI and RZIA (but please don't ask me which name belongs to which address!).
Giving a host several nicknames can be convenient if you want to specify your favourite host providing a special service with that name, as is commonly done with FTP-servers. The first (leftmost) name is usually the real (canonical) name of the host.
Besides giving nicknames, it's also convenient to give a host's full name (including domain) as its canonical name, and using only its hostname (without domain) as a nickname.
Important: There must be an entry mapping localhost to 127.0.0.1!