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IRC Documentation · Intermediate

Understand IRC numeric responses

A numeric reply is a message whose command is a three-digit code. The code and parameters define the structure; the final explanatory text is for display and may vary by server or language.

Dialova Team · Verified on

Read the structure rather than parsing a sentence #

NAMES replies addressed to client Alice
:irc.example 353 Alice = #atelier :@Alice Bob
:irc.example 366 Alice #atelier :End of /NAMES list

353 is the numeric command here. Alice is the recipient of the reply; #atelier and the list of nicknames are parameters useful to the client. The end-of-list phrase is not a stable identifier to recognize word for word.

Common references #

CodeUsageImportant note
001Welcome after registrationDo not equate this with a simple TCP opening.
005ISUPPORTDescribes server properties; this is not a CAP ACK.
311 / 318Start and end of WHOIS informationMultiple responses may interleave.
332 / 333Topic and associated metadata333 is a common practice, not the entire TOPIC response.
353 / 366Start and end of NAMES listThe list may be fragmented.
401Target not foundDoes not grant permission to bypass network policy.
482Insufficient channel privilegesVerify the actual role, not just the client menu.
903 / 904SASL success / failure.Therefore, 9xx codes are not all successes.

Historical responses and extensions. #

The RFCs describe a historical baseline, not all current responses. IRCd and extensions add codes; a client must be able to display or ignore them gracefully without inventing an interpretation. WHOIS can thus expose additional information depending on the network and permissions.

The 4xx and 5xx families contain many errors, but this heuristic does not replace the mechanism's documentation. Modern extensions also use structured responses like FAIL, WARN, or NOTE.

Associate the response with the correct action. #

A client can receive events and multiple responses simultaneously. Do not assume that "the next message received" is the response to the last command. Respect target parameters and end markers; labeled-response, when available, addresses more advanced correlation needs.

Sources & Verification

Examples use pseudonyms and fictional domains, except for explicitly documented connection points. Network-specific extensions and settings are noted in the text.