歴史

SSTP

[1] 伺か - SSTPプロトコル (2007-09-14 12:30:05 +09:00 版) http://usada.sakura.vg/contents/sstp.html##statuscode

[2]

420 Refuse ゴーストが SSTP の受信を拒否

PEP (HTTP)

[3] PEP - an Extension Mechanism for HTTP (1998-04-07 21:31:46 +09:00 版) http://www.w3.org/TR/WD-http-pep#_Toc404743960

420 Policy Not Fulfilled

SIP

[4] RFC 3261 - SIP: Session Initiation Protocol (2012-01-09 20:48:30 +09:00 版) http://tools.ietf.org/html/rfc3261#section-21.4.15

420 Bad Extension

[5] Error Codes & Responses | Twitter Developers ( (2012-02-19 13:24:15 +09:00 版)) https://dev.twitter.com/docs/error-codes-responses

[6] Rate Limiting | Twitter Developers ( (2012-08-17 02:45:08 +09:00 版)) https://dev.twitter.com/docs/rate-limiting

[7] RFC 2660 - The Secure HyperText Transfer Protocol ( (2013-07-20 22:21:48 +09:00 版)) http://tools.ietf.org/html/rfc2660#section-5.2.2

[8] List of HTTP status codes - Wikipedia, the free encyclopedia ( (2013-10-01 11:44:11 +09:00 版)) http://en.wikipedia.org/wiki/List_of_HTTP_status_codes#420

[9] RFC 2660 - The Secure HyperText Transfer Protocol ( (2014-11-09 14:12:37 +09:00 版)) http://tools.ietf.org/html/rfc2660#section-5.2.2

[10] PEP - an Extension Mechanism for HTTP ( (1998-04-08 06:31:46 +09:00 版)) http://www.w3.org/TR/WD-http-pep#_Toc404743960

[11]

Connecting to a streaming endpoint | Twitter Developers (2015-03-05 11:50:39 +09:00 版) https://dev.twitter.com/streaming/overview/connecting

Rate limited clients will receive HTTP 420 responses for all connection requests.

[12]

Connecting to a streaming endpoint | Twitter Developers (2015-03-05 11:50:39 +09:00 版) https://dev.twitter.com/streaming/overview/connecting

420 Rate Limited
The client has connected too frequently. For example, an endpoint returns this status if:
A client makes too many login attempts in a short period of time.
Too many copies of an application attempt to authenticate with the same credentials.