> Mark.Andrews;
>
> > None of the issues hear have changed with the introduction of IPv6.
>
> With IPv6, trancation is morelikely, which is the change.
>
> > You have glue being dropped today because sites have excessive
> > numbers of nameservers. Try asking for a really long name from
> > the root servers under com or net. You may only have one glue
> > record.
>
> With your example of query for "com." all the name servers of which
> are under "net." all the name servers of which are under "net.",
> glues are not "necessary" that the behaviour is fine.
>
> A problem is that the root server gives similar reply to similar
> query for "vix.net".
>
> Then, there is a subtlity whether glues are "necessary" or not.
>
> In theory, it may be and the implementation is broken.
>
> In practice, it may not be, if name servers do not gives up against
> the obvious delegation loop (all the name servers are under zone cut)
> and ask As of "?.gtld-servers.net", because query for
> "?.gtld-servers.net" gives all the "necessary" glues without
> truncation.
>
> In practice with both A and AAAA, it is, because explicite query
> for "?.gtld-servers.net" will also be truncated.
>
> If the case is too difficult to understand, just consider a
> case of "vix.net" with just a single AAAA and no A glue
> returned. Then, IPv4 only host is at a loss.
No. It just asks the parent the missing glue records
individually. In this case for ?.gtld-servers.net/A records
from the root servers.
The only time it will loose is when the NS RRset is too big
to even allow the requested glue RRset to be added
preferentially to the additional section.
If the parent server is really smart it will reserve enough
space for the requested glue RRset. Attempt to add the NS
RRset. If that fails it will set TC and return the message.
Otherwise it will then release the reserved space for the
glue RRset. Add the glue RRset then add any other additional
records that will fit.
The reserved space is 16 octets per A and 28 octets per AAAA.
Older parent servers that promote glue to answer don't even
have this problem.
> Masataka Ohta
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: [EMAIL PROTECTED]
.
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