On 2024-10-23 1:38 AM, Peter Thomassen wrote:
CAUTION: This email is from an external source. Be careful when
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Hi Mark,
On 10/23/24 01:16, Mark E. Jeftovic wrote:
But most providers do it via CNAME flattening, so at the end of the
process, they aren't really CNAMEs, they're A recs.
But this will not work for Substack custom domains - and after going
back and forth with their support, who took it up with some ops, it
turns out that custom domains /at the apex/ on Substack will /only
work/ when the query returns, literally, a CNAME when queried.
Hm, so why is that?
From Substack's web server perspective, the client is making an HTTP
request to their IP address, and it does not matter (in fact, the web
server does not know) whether that IP address is looked up from a
CNAME or via an A record directly. In the latter case, it also does
not matter whether that A record is maintained manually or
automatically (via CNAME flattening).
I believe it's because *target.substack-custom-domains.com* runs on
Cloudflare CDN and they either need the custom domain to be /on
Cloudflare/ nameservers or implemented the same way as Namecheap (which
the original email email outlined).
Presumably if its the former, it's because CF can then use some internal
mapping to know which custom domains are in use, for the latter, well,
that's why I asked. It shouldn't make a difference, because the resolver
should just re-query the CNAME target and wind up with A/AAAA recs
anyway (right?)
After I sent the original message I realized that the example domain
name Substack support gave me, doesn't even map to a custom domain
there, it just redirects to main substack page, so now I'm wondering if
perhaps I'm still not getting a totally accurate explanation from Substack.
- mark
--
Mark E. Jeftovic <mar...@easydns.com>
Co-founder & CEO easyDNS Technologies Inc.
+1-(416)-535-8672 ext 225
/"Never expect a thing you do not want,
and never desire a thing you do not expect."
-- Bob Proctor /
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