Can I check whether a business's domain names are actually registered to the company?

Yes, and it's a quick, worthwhile check. Domain name registration information is generally available through a public WHOIS lookup or the specific domain registrar, though privacy services some registrars offer can mask the underlying registrant's identity from a public search — in those cases, you'll need the seller to confirm registrant details directly, or have your lawyer request registrar account access as part of due diligence rather than relying only on a public search.

This matters for the same reason website and social media ownership matters: domain names are frequently registered in a founder's personal name, or in the name of a web developer or marketing agency that originally set them up, rather than the corporation. If the domain isn't actually owned by the entity you're buying, the seller (or a third party) could retain control of it after closing, which for many businesses means losing their website and any email addresses built on that domain overnight.

Confirm registrant details before closing, and require domain transfer (along with registrar account access) as a specific, itemized closing deliverable in your purchase agreement, not an informal promise to be sorted out later. A Treadstone business lawyer can make sure this is properly documented.