Networking Question of the Week By Guest Authors November 22, 2011 Every other week we post TCP/IP, subnetting, and other networking certification questions to help you prep for the exams. Which IP application does the well-known port number 23 reference? FTP SMTP TELNET TFTP The correct answer is 3. FTP is referenced by 20, SMTP is referenced by 25, and TFTP is referenced by 69. Related Courses TCP/IP Networking Understanding Network Fundamentals In this article CertificationNetworkingTechnologysubnettingtcp/ip Join the Conversation Cancel Reply Will not be published. Website Notify me of follow-up comments by email. Notify me of new posts by email.