What is DNS?

DNS is the lookup that happens before any page loads. You type a name, and DNS returns the numeric address of the server that answers for it, the way a contacts app turns a person's name into a phone number. Every domain has a set of records that say where its traffic should go. The most relevant ones for sharing are the records that point a domain, or a subdomain like links.yoursite.com, at a host.

This is the machinery behind what a custom domain is. When you want your own address on a share link instead of the default, you add a DNS record at your registrar pointing to NudgeHost, and from then on the domain resolves to your hosted files. The feature itself, using your own domain, lives on a paid tier, so upgrade to Pro is where that starts. The hosting underneath is the same as any other page you would put an HTML file online.

The one quirk worth knowing is propagation. A DNS change is not always instant, because the answer is cached at many points along the way, so a new record can take anywhere from minutes to a day to be seen everywhere. That is normal and not a sign anything is broken. Once it settles, the domain points where you told it, and the certificate that secures it is issued automatically.