The TTL for CNAME records does not work in any way differently than other records.
Let us imagine a recursive resolver through which the above goes.
It then fills its cache with:
www.example.com CNAME valid for 600s
prod.myzone.l2.company.example CNAME valid for 600s
ssl-endpoint-12345.hostcorp.example A valid for 60s
If someone later query ssl-endpoint-...
Not at all. Period.
DNS does not do browser redirects. What you do is have a website react to the old domains and issuing a HTTP Permanent Redirect (response 301).
A redirect like this CAN NOT BE DONE IN DNS.
Now, this may not be possible with Network Solutions hosting - but that is THEIR limitation, not a technical one.
The actual directory in nginx can be anything, you just need to set the root directive properly in the virtual host for the subdomain.
I would advice to have a completely separate directory for each virtual host, for example:
If you have subdomain files at /var/www/example.com/subdomain directory, you might have ...
Add the sub domains as entries in the same server config file and point the sub domains to the specific file path containing the sub domains files. Creating a sub directory should work. https://stackoverflow.com/questions/17568981/nginx-two-subdomain-configuration
Update cnames with your dns provider.
You can use nginx -t to check the syntax in you files.
it seems like the answer is basically that the original architects never thought it would be useful or something equally short sighted
It's important to understand that the Domain Name System (DNS) was replacing an arrangement that used a globally cloned version of /etc/hosts across every computer on the internet at the time, so reliability and fast ...