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If I stop an Amazon EC2 instance and then start it again it will loose it's address. How do I prevent that?

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migrated from Mar 20 '11 at 7:16

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You cannot prevent that, the public DNS of any instance cannot be relied upon to be constant. Either:

  • Add a dynamic DNS service to the instance so that it updates a dynamic DNS address somewhere and you use that dyn DNS address, or:
  • Use an elastic IP. When you stop and start the instance, ensure the IP address is associated with that instance. Note that unmapped IP address cost when the instance is off. You need to add an A record to your DNS entry to map to that IP address. If the instance is off a lot, you'd better using route 53 DNS for the domain with a short TTL on your specific domain. That way you can remap the A record to your elastic IP fast.
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Perfect! That's exactly what I want to know. Thanks :-) – Anonymous Mar 18 '11 at 12:58

Depending on what you're trying to do, you might want to consider putting an elastic load balancer in front of an auto scaling group which contains your instance(s). Instances can come and go, but you only need to know the endpoint of your ELB. Note: ELB's are public. This is also the endpoint for your SSL certs.

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