Different ips for virtual servers?

So you know when you create a server, and you use the external ip not the pcs ip but the one for internet… often looks like 86.128.96.8 …

Well, how would I assign a different external ip for virtual machines? since I am trying to set up a server cluster thingie mabob and I’m wondering how you would connect to a different one with an assigned ip?

for example:

86.128.96.8 goes to Virtual Server One
86.128.96.9 goes to Virtual Server Two
86.128.96.10 goes to Virtual Server Three

and so on…

any ideas?