An application calls smc_connect_ex to connect to a server. When establishing a connection, smc_connect_ex sets up communication with the network, logs in to the server, and communicates any connection-specific property information to the server. A connection to Adaptive Server writes dbcc traceon messages to the Adaptive Server error log. You can ignore these messages.
For example, if the server supports network-based user authentication and the client application requests it, then Client Library and the server query the network’s security system to see if the user (whose name is specified by SMC_PROP_USERNAME) is logged in to the network.
See the code sample on page 22.