You must provide a set of external services before you deploy the components of this VMware Validated Design. External Services OverviewExternal services include Active Directory (AD), Dynamic Host Control Protocol (DHCP), Domain Name Services (DNS), Network Time Protocol (NTP), Simple Mail Transport Protocol (SMTP) Mail Relay, File Transfer Protocol (FTP), and Certificate Authority (CA). Physical Network RequirementsBefore you start deploying the SDDC, provide certain physical network configuration. VLANs, IP Subnets, and Application Virtual NetworksBefore you start deploying the SDDC, you must allocate VLANs and IP subnets to the different types of traffic in the SDDC, such as ESXi management, vSphere vMotion, and others. For application virtual networks, you must plan separate IP subnets for these networks. Host Names and IP AddressesBefore you deploy the SDDC following this VMware Validated Design, you must define the host names and IP addresses for each of the management components deployed. Some of these host names must also be configured in DNS with fully qualified domain names (FQDN) that map the host names to their IP addresses. Time SynchronizationSynchronized systems over NTP are essential for the validity of vCenter® Single Sign-On and other certificates. Consistent system clocks are important for the proper operation of the components in the SDDC because in certain cases they rely on vCenter Single Sign-on. User Accounts and GroupsBefore you deploy and configure the SDDC in this VMware Validated Design, you must provide a specific configuration of Active Directory users and groups. You use these users and Active Directory groups for application login, for assigning roles in a tenant organization, and for authentication in cross-application communication. Active Directory Computer ObjectsYou must create Active Directory computer objects for the vRealize Automation IaaS virtual machines, so that they can join the Active Directory domain during the automated SDDC deployment by using Cloud Builder. Datastore RequirementsFor certain features of the SDDC, such as backup and restore, log archiving, and content library, you must provide secondary storage.