View Source: AAAAvsA6 - Waikato Linux Users Group

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For [IPv6] there are two types of [DNS] ResourceRecord, <tt>AAAA</tt> and <tt>A6</tt>.

<tt>AAAA</tt> is the simple one -- it works just like an <tt>A</tt> record in [IPv4], but with more bits.

<tt>A6</tt> supports fragments of [IPv6] addresses. You can say <tt>example.com</tt> has the fragment <tt>2002:c000:0201</tt>, <tt>engineering.example.com</tt> has "the example.com fragment" + <tt>:0001</tt>, and <tt>foo.engineering.example.com</tt> has "the engineering prefix" + <tt>:0000:0000:0000:0001</tt>.  This means that when <tt>example.com</tt> renumbers, they change just the one ResourceRecord for <tt>example.com</tt> and  all of their machines have been renumbered.

Some people complain that <tt>A6</tt> is too complicated, and prone to problems:
* What is the [TTL] on the response if the fragments all have different lifetimes?
* What's the status of it if some of the entries (but not all of them) are signed with [DNSSEC]?
* What protection is there against [DoS]?

The <tt>A6</tt> people say that it's necessary for networks that regularly change [IP] address (eg: networks that use a dynamic 6to4 address).

<tt>A6</tt> in general is the newer standard, and <tt>AAAA</tt> is the older standard, however, there doesn't yet appear to be much momentum for <tt>A6</tt> support.

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CategoryDns

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Last edited on Sunday, November 28, 2004 11:43:39 am by AristotlePagaltzis

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