Which DHCP option is used by video endpoints to locate the Cisco Communications Manager TFTP server to download the endpoints configuration?

DHCP option 43 carries vendor-specific information used by various vendors, but is not the standard option used by Cisco voice and video endpoints to locate a TFTP server.

DHCP option 82 is the relay agent information option used by DHCP relay agents to pass subscriber information, not for TFTP server discovery.

DHCP option 150 is a Cisco-specific extension that provides one or more TFTP server IP addresses to endpoints, enabling them to contact the TFTP server and download their configuration and firmware from Cisco Unified Communications Manager. It is preferred over the standard option 66 in Cisco deployments because it supports multiple TFTP server addresses for redundancy. Without this option, endpoints cannot locate the CUCM TFTP server and will fail to register.

DHCP option 176 is used by Avaya IP phones for their configuration parameters, not by Cisco endpoints.

DHCP option 242 is also an Avaya-specific option for phone provisioning and is unrelated to Cisco Communications Manager TFTP discovery.