If you are using a Teradata database, you need to set the TDPID parameter on the machine where your Teradata utilities (FEXP,MLOAD, BTEQ etc) are installed by adding an entry in the HOSTS file.
Ex in Windows XP OS, you can find the host file in C:\WINDOWS\system32\drivers\etc directory.
In the HOSTS file, enter a line in the following format:
172.20.176.208 tdatsvrname tdatsvrCOP1
where tdatsvrCOP1 is the alias for the remote server. The alias must begin with an alphabetic string and end with the COP n suffix, where n is a number between 1 and the total number of applications processors that are associated with the Teradata communications processor. Then Save the HOSTS file.
In logon file you can give the connection sting as