Some TLDs have a different way for nameservers registration and cannot be registered using the Nameserver Registration option. These TLDs are .DE, .EU and .FR.
NOTE 1: Prior to registration of personal nameservers you need to ask your hosting provider to create the corresponding A records for them in your domain name zone file. This can be done in the DNS or Zone Management menu of your hosting control panel. You might need to contact your hosting company for assistance with setting up these records.
NOTE 2: Currently, it is possible to register a server with an IPv4 address only through the NityGity interface. If you would like to register it with an IPv6 address, please contact our Support Team for assistance.
NOTE 3: Please note that the IP-addresses of each nameserver set for a .DE domain should differ by at least one number in any octet. Also at least one of them must be connected via IPv4.
Once the zone file is created, you can proceed with nameservers registration. This allows to create glue records for your servers at the Registry:
1. Sign into your NityGity account (The Sign In option is available in the top hat of the page).
2. Select the Domain List menu in the left sidebar and click on the Manage button in front of the domain name: 
3. Find the Nameservers section and select Custom DNS from the list:
4. Enter the nameservers in the following format and save changes using a checkmark icon:
IPaddress--ns2.domain.de
Please note that you should put 2 (two) dashes and NO spaces between the IPv4 address and the nameserver:
The domain will be pointed to the created nameservers once the changes are saved. Please give them 24-48 hours to propagate on the web.
That's it!
If you have any questions, feel free to contact our Support Team.