How do cloud instance domain names work?

wizdum

[H]ard|Gawd
Joined
Sep 22, 2010
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I have been playing around with Microsoft's Azure and starting thinking about how DNS resolution works with all these "cloud" providers. If I start up 10 different virtual servers (that are not web servers), I get 10 different domain names (mystuff.cloudapp.net, mystuff.blob.core.microsoft.net, etc.). They can't be giving out a public IP for each one of these domains, right? That would get expensive quickly. Port forwarding can be used to map ports on a public IP address to different internal servers, but then everyone would need to use a different, non-standard port for their service. Are they somehow pointing public domain names at private IP addresses (with something in the middle to properly route them)?

Or do they just have a metric-frack-ton of IP addresses so they can afford to hand them out like candy?
 
Damnit. Why can't reality be as interesting as the world inside my head.
 
Host headers? That's how I run multiple sites off my single IP at home.

Yeah, I have been doing that with websites. I was hoping there was a similar method for running other types of services (email, FTP, databases, game servers, etc.) as well. The way it worked in my head is this: vm1.mysite.com, vm2.mysite.com, vm3.mysite.com, etc all point to 10.10.10.10. 10.10.10.10 is running a DNS and routing service that "knows" vm1.mysite.com needs to point to 192.168.1.50, vm2.mysite.com points to 192.168.1.51, etc.
 
Most of it is proxy. I am more familiar with aws where you can choose only an internal IP to your instance or a true public IP.
 
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