System Resolver Test App?
barmar at alum.mit.edu
Thu Nov 12 06:48:02 UTC 2009
In article <mailman.971.1257996722.14796.bind-users at lists.isc.org>,
"david at from525.com" <david at from525.com> wrote:
> I think between Stephane's test app and some snoop data I have a better
> idea of what is going on. It seems as if the local resolver starts by
> issuing ipv6 requests to the three name servers mentioned in resolv.conf.
Do you mean that it's issuing requests using IPv6, or it's using IPv4 to
send requests for AAAA records?
> The first two valid DNS servers (not configured for ipv6) each respond
> back stating they are not authoritative for the domain in question causing
> the subsequent servers to be queried. The resolver finds itself querying
Which servers are you talking about now, the servers in resolv.conf, or
the servers for the domain you're querying? The latter should not
respond that they're not authoritative. Authority is not specific to IP
versions, it just goes by names. A server is either authoritative for
foo.com or it isn't, it can't be authoritative for foo.com's IPv4 data
but not for its IPv6 data.
> the third bogus name server and has to wait for the 5 second time out. The
> resolver then repeats the whole process for ipv6 adding another 5 seconds
> to the delay (total of 10 now). The resolver then finally starts the whole
> process again for ipv4 and gets the proper answer with the first query.
If you're not actually using IPv6, you might consider disabling it on
your system. That should stop all the unnecessary v6 lookups.
Barry Margolin, barmar at alum.mit.edu
*** PLEASE don't copy me on replies, I'll read them in the group ***
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