DeNIC, the .DE registry, requires that name servers are properly preconfigured before delegating the domain. This rule applies to all domain updates and registrations.
Technical name server requirements
The requirements regarding the nameserver predelegation check can be found at DENIC's website:
Registry-Based Check
The registry provides a web-based tool to check the DNS setup for a domain. The test shows whether there are setup errors for one or more name servers:
Enter the .DE domain and then the name servers. Entering the IP addresses is optional. Then click on EXECUTE, as shown in the screenshot below:
A banner with the notice Check failed will be displayed if the pre-delegation check fails and the description(s) in the Messages section will let you know what failed exactly, as shown in the screenshot below. You can obtain more details by clicking on the error code number:
Otherwise, a green banner with the text Check successful will be displayed.
Internal Check
You can also check the name servers with the CheckDNS command. For example:
command=checkdns
domain=example.de
nameserver0=ns1.nameserver.com
nameserver1=ns2.othernameserver.com