What do I need to do to make my website available under IPV6? My site is running on Amazon Web Services (AWS) behind a load balancer. I just saw that Amazon has announced support elastic load balancers via IPV6.

What settings do I need to enable at Amazon? What DNS changes do I need to make? How can I test my site to ensure it is working?


I always save my steps in a text editor, here's what I put but you can probably find AWS docs super easily by Googling your question. Probably the same thing.

Run the following command replacing the values wrapped in carrots with your information:

aws elbv2 set-ip-address-type --load-balancer-arn arn:aws:elasticloadbalancing:<us-east-example>:<some-numbers>:loadbalancer/app/the-load-balancer/<random-string> --ip-address-type dualstack

Now update the dns record for the load balancer


With this IPv4 requests will resolve A, and IPv6 will resolve AAAA.

Dualstack Requirements (from AWS)

You can set the IP address type when you create the load balancer and update it at any time. Note that an existing internal Application Load Balancer can't be updated to dualstack mode. You must recreate the Application Load Balancer and configure it as dualstack.

  • VPCs and subnets that you specify for the load balancer must have associated IPv6 CIDR blocks.

  • The route tables for the load balancer subnets must route IPv6 traffic.

  • The security groups for the load balancer must allow IPv6 traffic.

  • The network ACLs for the load balancer subnets must allow IPv6 traffic.

Associate an IPv6 CIDR block with a VPC

aws ec2 associate-vpc-cidr-block \
    --amazon-provided-ipv6-cidr-block \
    --ipv6-cidr-block-network-border-group <region>  \
    --vpc-id vpc-<example-vpc>

  • That doesn't sound too bad. Basically "enable dualstack then put in AAAA records." I still don't know how I would test that my site is available over IPV6 though. My ISP at home is still IPV4 only. Dec 24 '21 at 3:31
  • I tried to implement this but I got the error "Selected subnets must have the CIDR block required by the IP address type." It looks like I need to change settings on my subnets or maybe create new subnets. I don't see anything obvious for enabling IPV6 CIDR blocks in my existing subnets. Do you know what I have to do for that? Dec 24 '21 at 10:26
  • 1
    I found it. In each subnet there is an "Actions" drop down with a menu item for "Edit IPv6 CIDRs". I needed to add a CIDR there and assign it a hexidecimal final value (like 01 for my first subnet and then 02) for my second subnet. Dec 24 '21 at 11:08
  • 1
    Can I edit your answer to add some details? Dec 24 '21 at 11:09
  • @StephenOstermiller Go for it. Good looks testing this out. Dec 24 '21 at 13:12

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