Is there a reason that the IPv6 standard uses AAAA rather than AA? I cannot find reference to AA or AAA records in DNS. Do the As indicate anything specific?

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    You're unlikely to get an authoritative answer to this, as it was decided nearly a quarter century ago; the answer, if it exists, was probably on a long-dead mailing list for which archves disappeared from the Internet many years ago. – Michael Hampton Mar 20 '18 at 22:39
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    @MichaelHampton AAAA is defined by RFC1886 and then RFC3596. The first one was draft-ietf-ipngwg-dns and the second draft-ietf-dnsext-rfc1886bis so you can go to the working groups. The first one has no more mailing lists archives but through the second ones you can find interesting threads, such as: mailarchive.ietf.org/arch/msg/dnsext/… or this ID: tools.ietf.org/html/draft-ietf-dnsext-aaaa-a6-01 or mailarchive.ietf.org/arch/msg/dnsext/… – Patrick Mevzek Mar 21 '18 at 1:49
  • @PatrickMevzek All of those mailing list threads and the I-D seem to be about AAAA compared to A6, something that happened many years after the events the OP is asking about. Is there something specific you wanted to call attention to? – Michael Hampton Mar 21 '18 at 3:06
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    @MichaelHampton Just the fact that not all is lost, a little search does provide some useful information... and AAAA vs A6 also gives explanations about why AAAA... – Patrick Mevzek Mar 21 '18 at 3:15

I take it this is a question specifically about the name of the RR type?

It obviously could have had a different name, the name AAAA for IPv6 address records is in reference to an IPv6 address (128 bits) being four times the size of an IPv4 address (32 bits).

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    For a bit of extra history: there was also an A6 type that could do hierarchical references where part of the address was defined in another A6 record etc. It got deprecated because of the added complexity. – Sander Steffann Mar 21 '18 at 0:10
  • Oh, the horrible knuckles! Yes, the early drafts had some (technically awesome) stuff in. And I'm pretty sure you're right about the size being the key; I don't think I can remember where I read it though. You could try asking the surviving early-Internet people, e.g. Gene Spafford is on Quora… – Will Crawford Mar 21 '18 at 4:03
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    @WillCrawford I'm not such an old-timer but I do recall learning that that was the reason sometime around 2000, so it's not a new explanation. And it has the right combination of silliness and obviousness to have been the original justification. – hobbs Mar 21 '18 at 4:12
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    … IPng was recommended in 1994, published as RFC 1752 in 1995. – Will Crawford Mar 21 '18 at 4:52
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    "The syntax of the AAAA resource record is exactly the same as the A record, except that the addresses take longer to type" — ;login: the magazine of usenix & sage (pdf) – Will Crawford Mar 21 '18 at 4:55

RFC 1035, which defines resource records for DNS, mentions the meaning of record type A as 'host address'. 'Host address' back then was of 32 bits.

RFC 3596 explains the new resource record for IPv6. It defines a new record type to be used to store an IPv6 address.

So the new record type should signify the address that is stored with it. The best way to do that is to compare IPv6 with IPv4, and so we have four A's - four times that of the IPv4 length.


A is nothing but an Address and Simple Difference between A and AAAA

A DNS Record Type define IPV4 Address size is 32bit number

AAAA DNS Record Type define IPV6 Address size is 128bit number (32*4 means A*4) number.

So we called as AAAA record

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