The server that cannot be configured during the installation phase when installing Cisco Unified Contact Center Express (UCCX) on Cisco Unified Computing System (UCS) servers is the SMTP server. The SMTP server is a server that enables the email functionality of UCCX, such as sending email notifications, alerts, and reports. The SMTP server cannot be configured during the installation phase, but it can be configured after the installation by using the Cisco Unified CCX Administration web interface12

The other options can be configured during the installation phase when installing UCCX on UCS servers:

Cisco Unified Communications Manager (CUCM) server: The CUCM server is a server that provides call control and device management for UCCX. The CUCM server can be configured during the installation phase by specifying the IP address or hostname, the username, and the password of the CUCM server. The CUCM server must be configured before the UCCX installation can proceed12

DNS server: The DNS server is a server that resolves hostnames to IP addresses and vice versa. The DNS server can be configured during the installation phase by specifying the IP address or hostname of the primary and secondary DNS servers. The DNS server is optional, but it is recommended to use it for easier management and troubleshooting12

NTP server: The NTP server is a server that synchronizes the time and date of UCCX with a reliable source. The NTP server can be configured during the installation phase by specifying the IP address or hostname of the primary and secondary NTP servers. The NTP server is mandatory, and the installation will fail if the UCCX server cannot reach the NTP server12

References: 1: Cisco Unified Contact Center Express Install and Upgrade Guide, Release 10.0(1) - Unified CCX Installation [Cisco Unified Contact Center Express] - Cisco 1 2: Cisco Unified Contact Center Express Install and Upgrade Guide, Release 10.0(1) - Unified CCX Configuration [Cisco Unified Contact Center Express] - Cisco 2