Elastic IP vs EC2 Public Hostname + Route53

amazon ec2amazon-elastic-ipamazon-route53amazon-web-services

We are evaluating to use Elastic IP on all of our ec2 instances, and we compare to the use of public EC2 hostname and Route53 (with a very short TTL to the public EC2 hostname & dynamic update DNS during instance boot).

We found out the use the EIP has no real value in fact, e.g.

  1. We can only use up to 5 EIP per region
  2. All the traffic thru EIP is counted as internet traffic, but for instance public hostname, when connecting from the internal network, it will be using internal IP which save us bandwdith/money
  3. You will also need to re-attach EIP after server stop/start, which is the same as re-attaching DNS for ec2 instance when the public hostname is changed.

Are there any important points I am missing?

Best Answer

  1. Amazon will happily lift this limit for you. In my experience, this only takes a few hours to go through.
  2. Correct, you should never use an EIP for internal EC2-to-EC2 traffic.
  3. Not if you use VPC (which you absolutely should if you're ever going to use more than a single standalone server). This also helps with point #2, as the internal IPs stay static through restarts/stops.
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