IPv6: DNS ‘glue’ support

What does this mean?

When you look up a DNS name (ignoring caching) such as “host.site.domain.com.au“, first “.au” is looked up against a well known list of servers [1] (the “root servers”), then “.com.au” is looked up against the result of the last search, then “domain.com.au”, “site.domain.com.au” [2], then finally “host.site.domain.com.au”.

In an all-IPv6 world, each of those lookups would have to occur over IPv6. That would mean each name-server, from the root (".") down to the name-server for “host.site.domain.com.au” would have to support IPv6. Currently, the root does support IPv6. Also, “.au” also has IPv6 name-server support (although the names-ervers are called “b1.audns.net.au” and “b2.audns.net.au (their real names are “adns1.berkeley.edu” and “adns2.berkeley.edu” and are hosted at University of California, Berkeley)

As can be seen from the table, whilst “.au” may have IPv6 support, none of the names underneath “.au” do have IPv6 support – with two exceptions. Those exceptions are “csiro.au” and “conf.au“. “conf.au” appears to have a name-server called munnari.OZ.au – one of the oldest (if not, the oldest active) name-server names in Australia (this server is registered to Thailand – see Wikipedia: Rob Elz).

TLDs

Domain IPv6 Glue?
Global
.com yes
.net yes
.org yes
.gov no
.edu yes
.biz yes
.info yes
.arpa yes
.us yes

Australia (.au)

Domain IPv6 Glue?
.au yes
.asn.au no
.com.au no
.net.au no
.id.au no
.org.au no
.info.au no
.conf.au yes
.edu.au no
.gov.au no
.csiro.au yes


[1]: Yes, what usually happens is a lookup for “.” against a local recursive name-server, I know.
[2]: Pretending that each level does not have any caching or authoritative records for the next level

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