For buyers contracting authority
Choose 72417000 when the deliverable is the domain name itself: registering it, renewing it, and managing the DNS records that resolve it. A contracting authority reaches for this code to acquire a portfolio of names, to consolidate domain management with one registrar, or to stand up and run a registry for a regional or national top-level domain.
The boundary that trips authorities is web hosting (72415000). Hosting is where the site and its files live; a domain name is the address that points to them. Many contracts buy both, so set the primary CPV code by whichever dominates the statement of work. If the contract is mainly about keeping names registered and DNS resolving, this is the code; if it is mainly about running the servers, that is hosting.
One more neighbour: a full internet-access arrangement with connectivity belongs under ISP services (72411000), not here. Reserve 72417000 for the naming and DNS layer.