Introduction
Delegating means setting a/the responsible name server for a zone. After delegation, the nameservers can independently manage host names and subdomains.
Jurisdiction
Delegation must be done by the the operator of the top domain level. If, for example, a new .de domain just needs to be registered, the provider of the top-level domain (TLD) de(DeNIC) needs to set up the delegation so that the forwarding name servers of the second level domain are registered in the zone.
If, by contrast, only a subdomain needs to be created (for example <technik.grossefirma.de>), then this may be set up as a zone administrator of the parent domain (<grossefirma.de>).
Procedure in the Domain Registration Robot
DeNIC and other registries only accept delegation requests from providers who have signed partnership agreements.
The registration and delegation of a domain at Hetzner is done via the Domain Registration Robot, described in the following article: Robot Domain Registration - Getting started
Delegating subdomains: Entries in the parent Zone File
See the article on creating a DNS Zone File.