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by cortesoft 2783 days ago
A lot of DNS providers these days will give you a pseudo-cname on apex... basically having the dns resolver do a lookup of another dns name and return that as an A record for the apex.
2 comments
guitarbill 2782 days ago
CloudFlare calls this CNAME flattening, right? [0][1] Personally, I always enjoy engineering solution that mean we're not stuck with old decisions forever. I chose the non-www as a teenager, and I'm glad 10+ years later I could add email to my domain no problem.

[0] https://blog.cloudflare.com/introducing-cname-flattening-rfc...

[1] similar discussion, 2014: https://news.ycombinator.com/item?id=7293512

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paranoidrobot 2782 days ago
Except that the IP that your DNS provider resolves your apex to may be on the other side of the planet.

Fine if all you are doing is 302 to the www. Variant, but otherwise no.

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X-Istence 2782 days ago
This is where the Client Subnet edns extensions come in handy. This allows the DNS provider to pass along the /24 the users IP address is in.

With an extra caching key, this can even be cached.

See https://developers.google.com/speed/public-dns/docs/ecs

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paranoidrobot 2782 days ago
And that also only helps if your DNS provider and the client's DNS servers also pass along that information correctly.
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tony101 2782 days ago
> "the IP that your DNS provider resolves your apex to may be on the other side of the planet"

Anycast addresses this issue, right?[1] Cloudflare uses Anycast for their IP addresses.[2]

[1] https://en.wikipedia.org/wiki/Anycast

[2] https://www.cloudflare.com/learning/cdn/glossary/anycast-net...

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paranoidrobot 2782 days ago
Only if your CDN uses Anycast. Not all of them do.
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paulddraper 2782 days ago
Yes. AWS Route 53 can do this for root or non-root records. They call these "ALIAS" records.
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pluc 2782 days ago
Those only work for AWS services though, CloudFlare CNAME flattening works with any endpoint by providing some sort of HTTP proxy
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twothamendment 2782 days ago
I wish there was a standard way to do the same thing. Route 53 is nice when I can use it, but it causes me pain on a regular basis because not all the domains I deal with are on Route 53.
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