DOMAIN’s can also be registered without a name server entry. Such a DOMAIN is inactive, i.e. it cannot be found in a browser-search.
If they appear for hosting at a later date, they can be entered in the DOMAIN Manager at any time.
Certain registry’s (for example.de,.swiss) require the entry of name server. With these DOMAIN’s Swizzonic automatically enters valid name servers. These are visible in WHOIS, but not in your user account.