You can use a Web browser to access an FTP server simply by putting ftp:// in front of the URL

(e.g., ftp://xyz.abc.com). If that server has FTP server software installed, then the FTP server will respond instead of the Web server. What is your browser doing differently to access the FTP server? Hint: This question is more difficult than it seems, because we haven’t explained how the server knows to pass certain types of packets to the right software (i.e., HTTP requests to the Web server software and SMTP packets to the e-mail software). At this point, don’t worry about it. Linking the network to the application layer is the job of the transport layer, which is explained in Chapter 5.