Elasticity of the cloud computing is a wonderful idea. You can get an instance of networked computer exactly when you need it and you only pay for the time when you actually use it. But while the virtual memory and hard disk is a “clean slate” created specifically for you, the IP address assigned to your instance may have been previously used by a spammer and it could be already on a “spam blacklist”. In an extreme case the whole IP address range can be marked as a source of spam. And this is exactly what happened to Amazon’s EC2: “Go Daddy blocks links to EC2 “.
The problem is the scarcity of IP addresses — Amazon.com doesn’t have enough addresses to give every user a fresh new IP address with the new instance. And the solution to this problem is called Internet Protocol version 6/IPv6:
The very large IPv6 address space supports 2128 (about 3.4×1038) addresses, or approximately 5×1028 (roughly 295) addresses for each of the roughly 6.5 billion (6.5×109) people alive today. In a different perspective, this is 252 addresses for every observable star in the known universe – more than seventy nine billion billion billion times as many addresses as IPv4 (232) supports.
This means that there will be enough IP addresses not only for the elastic clouds but also PDAs, cell phones and other IP based clients. On the other hand it will make the “spam blacklists’ irrelevant since every piece of spam can come from a different IP address: “If the earth were made entirely out of 1 cubic millimeter grains of sand, then you could give a unique IPv6 address to each grain in 300 million planets the size of the earth” .