You must provide a set of external services before you deploy the components of the VMware Validated Design. External Services Overview in ROBOExternal services include Active Directory, DHCP, DNS, NTP, SMTP Mail Relay, an FTP server, and certificate services. VLANs, IP Subnets, and Application Virtual Networks in ROBOBefore you start deploying the ROBO SDDC, you must allocate VLANs and IP subnets to the different types of traffic in the remote office and branch office, such as ESXi management, vSphere vMotion, and others. For application virtual networks, you must plan separate IP subnets for these networks. DNS Names and IP Addresses in ROBOYou must provide the necessary DNS names and IP addresses required by the ROBO SDDC deployment. Time Synchronization in ROBOSynchronized systems over NTP are essential for vCenter Single Sign-On certificate validity, and for the validity of other certificates. Consistent system clocks are critical for the proper operation of the components in the ROBO SDDC because in certain cases they rely on vCenter Single Sign-on. Active Directory Users and Groups in ROBOBefore you deploy and configure the ROBO SDDC in this validated design, you must provide a specific configuration of Active Directory users and groups. You use these users and groups for application login, for assigning roles in a tenant organization and for authentication in cross-application communication. Certificate Replacement in ROBOBefore you deploy the ROBO SDDC, you must configure a certificate authority and generate certificate files for the management products. According to this validated design you replace the default VMCA- or self-signed certificates of the management products with certificates that are signed by a Certificate Authority (CA) during deployment.