For this website, I wanted a way to create so-called "review apps" so I can preview pull requests on
preview-<PR>.website.sven.luijten.dev. This turns out to be a built-in feature with Vercel, but their documentation
instructed me to point luijten.dev's nameservers to theirs.
I wanted to find a way around this so that I could keep the nameservers for all my domains in Cloudflare. After a quick
Google search, I came across the NS record you can add to your domain. This allows you to "delegate" the nameservers
for a given (sub)domain down to another authoritative nameserver, like Vercel's.
Since I manage my DNS with DNSControl, I added an NS record for
website.sven pointing to Vercel's nameserver:
D('luijten.dev', REG_NONE, DnsProvider(DNS_CLOUDFLARE),
// ...
NS('website.sven', 'ns1.vercel-dns.com.'),
NS('website.sven', 'ns2.vercel-dns.com.')
);
This tells all traffic to website.sven.luijten.dev and any subdomain (so <anything>.website.sven.luijten.dev) to
use Vercel's nameservers.