r4 - 2014-02-02 - 23:56:26 - HarlanStennYou are here: NTP >  Dev Web > DevelopmentIssues > KoDResponses
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Kiss-o'-Death (KOD) Responses

Related Topics: NtpProtocolResponseMatrix

KOD codes and meanings

Per RFC5905, Section 7.4 and Figure 13.

DENY - Access denied by remote server

The client MUST demobilize any associations to that server and stop sending packets to that server.

Question: For how long?


RATE - Rate exceeded. The server has temporarily denied access because the client exceeded the rate threshold.

The client MUST immediately reduce its polling interval to that server and continue to reduce it each time it receives a RATE kiss code.

Question: How long before the client might try and ask more frequently?


RSTR - Access denied due to local policy

The client MUST demobilize any associations to that server and stop sending packets to that server.

Question: For how long?



These codes are unregistered and experimental codes. Unless your implementation recognizes the particular code, it MUST be ignored.

"For how long"?

What are good numbers for how long one should "back off" after a KOD response? "Forever" seems way too long. This is similar to the question of "how long should we use an IP we got from a DNS name before we re-resolve it?" In this latter case, Harlan can easily see the case where the TTL value is likely "too short". But that's a different question for a different topic...

  • Perhaps it could be a function of the ppoll value from the received KOD packet with some hard-coded minimum and maximum? -- MiroslavLichvar - 28 Jan 2014

Is the KOD mechanism really useful?

  • For enforcement, no. As an advisory mechanism, certainly. Think of them as an error return code from any other type of request. -- BrianUtterback - 22 Jan 2014

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