Cisco Networking Academy Program CCNA 1 and 2 Companion Guide, Revised part 53 is the Cisco approved textbook to use alongside version of the Cisco Networking Academy Program CCNA 1 and CCNA 2 web-based courses. The topics covered provide you with the necessary knowledge to begin your preparation for the CCNA certification exam (640-801, or 640-821 and 640-811) and to enter the field of network administration. | Page 489 Tuesday May 20 2003 2 53 PM Windowing 489 Table 9-1 Reserved TCP and UDP Port Numbers Decimal Port Number Keyword Description 0 Reserved 1 to 4 Unassigned 5 Rje Remote job entry 7 Echo Echo 9 Discard Discard 11 Users Active users 13 Daytime Daytime 15 Netstat Who is up or netstat 17 Quote Quote of the day 19 Chargen Character generator 20 ftp-data File Transfer Protocol data 21 ftp File Transfer Protocol 23 telnet Terminal connection 25 Smtp Simple Mail Transfer Protocol 37 Time Time of day 39 Rlp Resource Location Protocol 42 Nameserver Host name server 43 nickname Who is 53 Domain Domain Name Server 67 Bootps Bootstrap protocol server 68 Bootpc Bootstrap protocol client 69 Tftp Trivial File Transfer Protocol 75 Any private dial-out service 77 Any private RJE service continues B Page 490 Tuesday May 20 2003 2 53 PM 490 Chapter 9 TCP IP Transport and Application Layer Table 9-1 Reserved TCP and UDP Port Numbers Continued Decimal Port Number Keyword Description 79 Finger Finger 80 HTTP Hypertext Transfer Protocol 123 Ntp Network Time Protocol 133 to 159 Unassigned 160 to 223 Reserved 224 to 241 Unassigned 242 to 255 Unassigned Numbers below 1024 are considered well-known port numbers. Numbers above 1024 are assigned port numbers dynamically. Registered port numbers are those registered for vendor-specific applications. Most are above 1024. As shown in Figure 9-12 end systems use port numbers to select the proper application. Originating source port numbers are assigned dynamically by the source host with some number greater than 1023. As an example a host attempting to connect to another using FTP sends a packet with a destination TCP port number of 21 FTP and a dynamically generated source port number such as 1028. This pair of port numbers destination and source defines the unique conversation between these hosts. If the same host initiates another FTP session to a second host the destination port still is 21 but the source port .
