The interfaces file is usually named SQL.ini on PC operating systems and interfaces, or interfac on Unix operating systems.
Like an address book, the interfaces file lists the name and address of every database server known to Open Client applications on your computer. When you use an Open Client program to connect to a database server, the program looks up the server name in the interfaces file and then connects to the server using the address.
The name, location, and contents of the interfaces file differ between operating systems. Also, the format of the addresses in the interfaces file differs between network protocols.
When you install SQL Anywhere, the installer creates a simple interfaces file that you can use for local connections to SQL Anywhere over TCP/IP. It is the System Administrator's responsibility to modify the interfaces file and distribute it to users so that they can connect to SQL Anywhere over the network.