Re: http://www.ntp.org/ => a blank page?

On Mar 9, 3:47 am, ma...@xxxxxxx (Danny Mayer) wrote:
Dave Hart wrote:
That's a bit misleading.  At the protocol level the queries are often
distinct, asking for A or AAAA records.  type=any will return both but
is not typically used in apps.  At the app level, if the app looks up
a name indicating both IPv4 and IPv6 addresses are desired, platform
and site policies come into play

getaddrinfo() which is used by all newer apps returns both IPv4 and IPv6
unless you specify a particular type. It has nothing to do with site
policy and they do not come into play. The query is controlled solely by
the app. The app may have additional controls on whether or not it wants
to query for IPv4, IPv6 or both.

You might want to spend a little time curling up with RFC 3484,
"Default Address Selection for IPv6"

http://www.rfc-editor.org/rfc/rfc3484.txt

With RFC 3484 support, getaddrinfo sorts its results so that
applications processinig the results in order follow the selected
policy. Given that the RFC came out of Microsoft Research, it should
be no surprise that a certain widely-used platform respects RFC 3484.
Take particular note of the policy tables described in RFC 3484 and
how they allow site policies to come into play.

It sounds like you use a disconnected IPv6 network alongside a
connected RFC1918 v4 network internally.  I wonder if you could get by
using only link-local addresses for your internal IPv6 network?  I
believe that would solve the problem because your stack would know it
can't connect to a global v6 address from a machine with only link-
local v6 addresses.

The stack has no knowledge of whether it can connect to a global IPv6
address. Only the routers will be able to do that.

Since link-local addresses by definition are not routable, routers do
not come into play. Any IPv6 stack understands the difference between
link-local and global addresses, and will not attempt to connect to a
global remote address using a link-local local address. Hence the
results Martin saw that only machines with IPv6 global addresses were
having trouble with names returning AAAA as well as A.

This may indeed be the best option for your configuration.  I wouldn't
call it a good solution, though.  Your machines should be able to
handle seeing AAAA records via IPv4-accessible DNS even if they can't
use them.  I'd dig into configuring the machines to use IPv6 as a last
resort before considering DNS server-based AAAA filtering.

It cannot be done by the DNS.

This reads as a non-sequiter. I have no idea what "It" is that cannot
be done.

Cheers,
Dave Hart
.

Relevant Pages

  • Re: http://www.ntp.org/ => a blank page?
    ... At the app level, ... getaddrinfowhich is used by all newer apps returns both IPv4 and IPv6 ... You might want to spend a little time curling up with RFC 3484, ... DNS makes no ...
    (comp.protocols.time.ntp)
  • Re: How to determine if IPv6 is installed (using VC++ 6.0)
    ... and find that your app puts up a dialog box saying "IPv6 ... better message would be "App X cannot detect a supported version of IPv6. ... IPv6 may or may not work yada, ... Second if he contacts support he may remeber to mention this message which ...
    (microsoft.public.win32.programmer.networks)
  • Re: http://www.ntp.org/ => a blank page?
    ... though the DNS server first returns an IPv4 ... At the app level, ... a name indicating both IPv4 and IPv6 addresses are desired, ...
    (comp.protocols.time.ntp)
  • Re: [PHP] $_SERVER["REMOTE_ADDR"] returning ::1
    ... Request it with an IPv6 domain/IP and REMOTE_ADDR will also be IPv6. ... This app uses this test to insure that the page being processed came from the same machine as was used to login to the app. ... If you really need to use IP then you can probably rely on it not switching between v4 and v6 if you're not using localhost. ... using the real ip addr solved my problem as far as my test install is concerned. ...
    (php.general)
  • Re: Request for suggestions re: architecture of IntraNet/Socket app[s]
    ... I am commissioned with determining the "right" architecture for an application for controlling movement of stock in a warehouse. ... Much of your system describes monitoring -- control implies schedule and tracking for purposes of changing system operation -- correct? ... If multiple machines can handle the pieces and some machines do different operations -- then there is an element of scheduling and a time frame in which to complete. ... separate RealTime system either from the IntraNet server app OR from another ...
    (borland.public.delphi.non-technical)