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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Key Applications and Application Protocols            9  TCP/IP File and Message Transfer Applications and Protocols (FTP, TFTP, Electronic Mail, USENET, HTTP/WWW, Gopher)                 9  Usenet (Network News) and the TCP/IP Network News Transfer Protocol (NNTP)                      9  TCP/IP Network News Transfer Protocol (NNTP)

NNTP Command Extensions 1 2 3 TCP/IP World Wide Web (WWW, "The Web") and the Hypertext Transfer Protocol (HTTP)

Reply Code Structure and Digit Interpretation

As with SMTP and FTP, NNTP reply codes can be considered to be of the form “xyz”, where “x” is the first digit, “y” the second and “z” the third.

The first digit indicates the success, failure or progress of the command in general terms, whether a successful command is complete or incomplete, and the general reason why an unsuccessful command did not work. The values of this digit are defined slightly differently than in SMTP and FTP. In some cases, the terminology is just simplified; for example, the second category is “Command OK” instead of “Positive Completion Reply”. Table 270 shows the specific meaning of the possible values of this digit.

The second digit categorizes messages into functional groups. This digit is used in the same general way as in SMTP and FTP, but the functional groups are different; they are described in Table 271.

This last digit indicates a specific type of message within each of the functional groups described by the second digit. The third digit allows each functional group to have 10 different reply codes for each reply type given by the first code digit.

As in FTP and SMTP, these “x”, “y” and “z” digit meanings are combined to make specific reply codes. For example, the reply code “435” is sent by the server if a client issues the IHAVE command but the server doesn't want the article being offered. The command was correct but the reply is negative, thus it starts with “4”, and the message is related to message distribution, so the middle digit is “3”.

NNTP Command Extensions 1 2 3 TCP/IP World Wide Web (WWW, "The Web") and the Hypertext Transfer Protocol (HTTP)