Yes, there are nameserver requirements. The Registry DENIC requires the following:• A minimum of 2 authoritative independent DNS is required. This means that the IP-addresses of each nameserver should differ by at least one number in any octet.• At least one of the IP addresses must be connected via IPv4. The same rules are applied for personal nameservers registration for .de domain names.Please be aware that it is not possible to assign nameservers to any .de domains that fail to meet DENIC’s requirements.If a domain does fail to meet these requirements, it will stop resolving and will show ‘failed’ status within Whois. If the domain status remains ‘failed’ for four weeks, it will be deleted by the registry and no refund will be given.