Re: Editors question: Removal of SIG RR Presentation format TTL optimisation

[Mark.Andrews@isc.org]

> Q: Should the optimization of omitting the original TTL from the
>    master file format representation of the SIG RR be removed from the
>    specification ?

	It should go.

> Some background:
> 
> RFC 2535 says:
> 
> 7.2. Presentation of SIG RRs
> 
>    If the original TTL, which applies to the type signed, is the same as
>    the TTL of the SIG RR itself, it may be omitted. The date field which
>    follows it is larger than the maximum possible TTL so there is no
>    ambiguity.
> 
> Input for discussion:
> 
> "Master file format" is a presentation format defined in RFC 1035 section
> 5, and is part of the base DNS specification.  The DNSSEC documents define
> presentation formats for the DNSSEC RR types, and it seems likely that
> DNSSEC-aware implementations will include at least one program which
> will parse this presentation format.
> 
> The optimization of the original TTL field results in a relatively minor
> saving in the presentation of what is usually a fairly large RR, and
> allowing the optimization increases the complexity of any code that must
> parse this RR format.
> 
> Should the original TTL field remain optional, or should the revised specs
> make it mandatory?
> 
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--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews@isc.org

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