Method for exchanging a predecessor domain registrar (Ro) for the authentication and configuration of digital certificates of IoT devices (G1 - Gn) with a new domain registrar (Rn), wherein the predecessor domain registrar (Ro) and the IoT devices (G1 - Gn) of a technical installation are stored in a device register (VH1, VH2) on the basis of blockchain technology, the method comprises the following steps: Determination by the predecessor domain registrar (Ro) of the number of nearby attestations needed; Entry of the new domain registrar (Rn) into the device register (VH1, VH2); Gathering of the nearby attestations of the respective IoT devices (G1 - Gn) by the new domain registrar (Rn), wherein a nearby attestation is provided by a respective IoT device (G1 - Gn); Checking of whether the new domain registrar (Rn) fulfils the defined number of nearby attestations of the predecessor domain registrar (Ro); Acceptance of the technical installation by the new domain registrar (Rn) as authentication and configuration entity of digital certificates for the IoT devices (G1 - Gn) of the installation; Sending of voucher requests by the IoT devices (G1 - Gn) of the installation to the new domain registrar (Rn); Forwarding of the voucher requests by the new domain registrar (Rn) to an authorisation authority (Auth1, Auth2); Checking by the authorisation authority (Auth1, Auth2) in the device register (VH1, VH2) of whether the respective IoT device (G1 - Gn) belongs to the new domain registrar (Rn), wherein, if the authorisation authority (Auth1, Auth2) establishes that the corresponding IoT device (G1 - Gn) belongs to the new domain registrar (Rn), the authorisation authority (Auth1, Auth2) issues a voucher for the corresponding IoT device (G1 - Gn) and sends the voucher to the corresponding IoT device (G1 - Gn); exchanging the predecessor domain registrar (Ro) for the authentication and configuration of digital certificates of IoT devices (G1 - Gn) with the new domain registrar (Rn). Determination by the predecessor domain registrar (Ro) of the number of nearby attestations needed; Entry of the new domain registrar (Rn) into the device register (VH1, VH2); Gathering of the nearby attestations of the respective IoT devices (G1 - Gn) by the new domain registrar (Rn), wherein a nearby attestation is provided by a respective IoT device (G1 - Gn); Checking of whether the new domain registrar (Rn) fulfils the defined number of nearby attestations of the predecessor domain registrar (Ro); Acceptance of the technical installation by the new domain registrar (Rn) as authentication and configuration entity of digital certificates for the IoT devices (G1 - Gn) of the installation; Sending of voucher requests by the IoT devices (G1 - Gn) of the installation to the new domain registrar (Rn); Forwarding of the voucher requests by the new domain registrar (Rn) to an authorisation authority (Auth1, Auth2); Checking by the authorisation authority (Auth1, Auth2) in the device register (VH1, VH2) of whether the respective IoT device (G1 - Gn) belongs to the new domain registrar (Rn), wherein, if the authorisation authority (Auth1, Auth2) establishes that the corresponding IoT device (G1 - Gn) belongs to the new domain registrar (Rn), the authorisation authority (Auth1, Auth2) issues a voucher for the corresponding IoT device (G1 - Gn) and sends the voucher to the corresponding IoT device (G1 - Gn); exchanging the predecessor domain registrar (Ro) for the authentication and configuration of digital certificates of IoT devices (G1 - Gn) with the new domain registrar (Rn).