Expand details on IPv6 with CloudFront and WAF.

Author: ClydeMachine

README.md

@@ -1421,7 +1421,7 @@ CloudFront
 
 ### CloudFront Tips
 
--	🐥**IPv6** is [now supported](https://aws.amazon.com/about-aws/whats-new/2016/10/ipv6-support-for-cloudfront-waf-and-s3-transfer-acceleration/)!
+-	🐥**IPv6** is [supported](https://aws.amazon.com/about-aws/whats-new/2016/10/ipv6-support-for-cloudfront-waf-and-s3-transfer-acceleration/). This is a configurable setting, and is enabled by default on new CloudFront distribution.
 -	🐥**HTTP/2** is [now supported](https://aws.amazon.com/about-aws/whats-new/2016/09/amazon-cloudfront-now-supports-http2/)! Clients [must support TLS 1.2 and SNI](https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/distribution-web-values-specify.html#DownloadDistValuesSupportedHTTPVersions).
 -	While the most common use is for users to browse and download content (GET or HEAD methods) requests, CloudFront also supports ([since 2013](https://aws.amazon.com/blogs/aws/amazon-cloudfront-content-uploads-post-put-other-methods/)) uploaded data (POST, PUT, DELETE, OPTIONS, and PATCH).
 	-	You must enable this by specifying the [allowed HTTP methods](https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/distribution-web-values-specify.html#DownloadDistValuesAllowedHTTPMethods) when you create the distribution.
@@ -1437,6 +1437,7 @@ CloudFront
 -	🔸If using S3 as a backing store, remember that the endpoints for website hosting and for general S3 are different. Example: “bucketname.s3.amazonaws.com” is a standard S3 serving endpoint, but to have redirect and error page support, you need to use the website hosting endpoint listed for that bucket, e.g. “bucketname.s3-website-us-east-1.amazonaws.com” (or the appropriate region).
 -   🔸By default, CloudFront will not forward HTTP Host: headers through to your origin servers. This can be problematic for your origin if you run multiple sites switched with host headers. You can [enable host header forwarding](http://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/RequestAndResponseBehaviorCustomOrigin.html#request-custom-headers-behavior) in the default cache behavior settings.
 -   🔸4096-bit SSL certificates: CloudFront do not support 4096-bit SSL certificates as of late 2016. If you are using an externally issued SSL certificate, you’ll need to make sure it’s 2048 bits. See [ongoing discussion](https://forums.aws.amazon.com/thread.jspa?threadID=148783).
+- Although connections from clients to CloudFront edge servers can make use of IPv6, [connections to the origin server will continue to use IPv4.](https://aws.amazon.com/about-aws/whats-new/2016/10/ipv6-support-for-cloudfront-waf-and-s3-transfer-acceleration/)
 
 DirectConnect
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