Remember this from the early internet?
The Admin-C role for .de domains was discontinued in May 2018. Other domain extensions may use different contact models.
What does Admin-C mean?
Admin-C stood for Administrative Contact and referred to a domain’s administrative contact person. Since May 2018, DENIC has no longer recorded this contact person for .de domains.
AN EXAMPLE IN PRACTICE
Where you might encounter it
In old domain records, you may find an Admin-C listed alongside the domain holder. This contact could handle administrative tasks. For current management of a .de domain, however, you must follow the current contact and administration rules of your provider and DENIC.
Further sources
From NetzTurm Decode. Clear explanations with historical context.