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08 Aug 2017
The Domain Name System has always been intended to be extensible.
The original spec in the 1980s had about a dozen resource record types (RRTYPEs),
and since then people have invented many more so now there are about 65 different RRTYPEs.
But if you look at most DNS zones, you'll only see a handful of types, NS, A, AAAA, MX, TXT,
and maybe SRV.
A lot of the other types are arcane or obsolete, but there are plenty that are useful.
Moreover, new designs like DKIM, DMARC, and notorously SPF have reused TXT records
rather than defining new types of their own. Why? It's the provisioning crudware.
While DNS server software is regularly updated to handle new RRTYPEs, the web based
packages that most people have to use to manage their DNS is almost never updated,
and usually handles only a small set of RRTYPEs.
This struck me as unfortunate, so I defined a DNS extension
language that provisioning sytems can use to look up the syntax of new RRTYPEs, so
when a new type is created, only the syntax tables have to be updated, not the software.
Paul Vixie had the clever idea to store the tables in the DNS itself (in TXT records
of course), so after a one-time upgrade to your configuration software, new RRTYPEs
work automagically when their description is added to the DNS.
The Internet draft that
describes this has been kicking around for six years, but with support from ICANN (thanks!)
I wrote some libraries and a sample application that implement it.
See more ...
Stable link is https://jl.ly/Internet/extlang.html
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