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I am reading amazon's pricing policy for elastic IP and there I can see the following sentence:

You can have one Elastic IP (EIP) address associated with a running instance at no charge. If you associate additional EIPs with that instance, you will be charged for each additional EIP associated with that instance per hour on a pro rata basis.

I have no problems with understanding pricing policy which is nicely explained there and in this answer. I have just one question: why should one need more than 1 IP linked to his instance?

P.S. it does not sound like programming issue to me, but highly related to programming, so if one thinks that is does not belong here - please feel free to migrate to another site

Community
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Salvador Dali
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    Until SNI is fully supported, you need multiple IPs to do SSL based virtual hosting. – datasage Mar 31 '14 at 03:26
  • @datasage thank you for your comment. If you would explain this in more details for people like me, who do not know what is SNI, this would be an amazing answer :-) – Salvador Dali Mar 31 '14 at 03:30
  • SNI is Server Name Indication. It allows multiple SSL hosts to share the same IP address. Unfortunately it requires client support to work. If you don't need to support IE on Windows XP or Android 2.x Clients, you could use it. – datasage Mar 31 '14 at 05:54
  • Actually, there are plenty of HTTP clients libraries for Android that does not support SNI. So there are probably many Android 4.x phones with apps that does not support SNI. https://github.com/loopj/android-async-http/issues/224. – Rune Schjellerup Philosof Oct 08 '14 at 19:28

1 Answers1

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Multiple EIPs only apply to VPC EIPs specifically.

So one use is to have many virtual hosts using different SSL certs like @datasage mentioned.

The other use relates to having multiple interfaces (Elastic Network Interfaces) attached to an instance in a VPC. As per the docs here are some uses :

  • Create a management network.
  • Use network and security appliances in your VPC.
  • Create dual-homed instances with workloads/roles on distinct subnets. (Apache/nginx virtual hosts fall into this category)
  • Create a low-budget, high-availability solution.
Rico
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