[dns-operations] Role of RFCs was Re: Problems resolving

Edward Lewis Ed.Lewis at neustar.biz
Tue Mar 17 14:16:42 UTC 2009

At 12:18 +0100 3/17/09, it doesn't matter who wrote:

>And 5.2 trumps 5.5?  I wouldn't count on that.

One thing I feel compelled to say about statements like the above is 
that an RFC is only an engineering document.  It is structured as 
guidance, not a prescription.  This was drummed into me while writing 
the wild card RFC, that RFC 1034, section 4.3.2 was not an outline of 
code, nor even pseudo-code, but a description of how to arrive an an 
outcome.  The RFC should include rationales and experiences (in 
operations) for what it describes.

An RFC is not quite a specification, no matter how close they get to 
that kind of language.  The original RFCs on DNS were much less 
formal than recent ones (1034 vs. 4034).  If RFCs were 
specifications, there would be testing procedures for conformance. 
There would also be some mechanism for updating an RFC in the event 
there was a mistake discovered later in the process.  And probably 
other things - I'm an RFC editor, not a specification writer.

RFCs don't trump each other, they don't internally trump themselves. 
RFCs obsolete others when new engineering think happens.  The 
entirety of the document has to be understood to get the point. 
Debating the finer points of an RFC is a symptom of "not getting it." 
The RFCs don't convey the rightness of a point, they are a recording 
of engineering thought.

RFCs are also not legally binding documents.  No one is required to 
abide by an RFC.  Legally binding documents are things like 
contracts, etc.  A contract may say "implement RFC WXYZ" with the 
understanding that the RFC is subject to interpretation.

Finally, an RFC is a consensus of those that worked on it (that's 
including reviewers).  Sometimes we feel as if an RFC somehow 
reflects universal consensus because anyone could have commented 
during the IETF discussions but the fact is that not everyone knows 
of the IETF, it's processes, or may even feel it is financially sound 
to even have an employee listen and participate in a working group 
(email list).  So, before believing an RFC is the final word in an 
argument, make sure the RFC considered the use case in dispute.

(Not that this applies to the .gov - DLV situation, but I felt I was 
on a roll.)
Edward Lewis
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