On 25-sep-2007, at 2:18, Mark Andrews wrote:
You are comingling way too many things here. Let me simply conclude
that foo.example.org is the first name that is tried and since it
exists what comes back for that name is what's going to be used.
Actually it isn't specified what should happen.
If you don't make AAAA queries most(all?) existing search
algorithms will continue to foo.example.net. Remember, in
the DNS, a name can exist yet have not records associated
with it (rcode=NOERROR ancount=0 is returned for all types).
Looks like you're right, at least as far as my Mac is concerned.
I set up two subdomains test1 and test2 with each the hosts a, b, c
and d with the following addresses:
IPv6 IPv4
a.test1 X X
b.test1 X -
c.test1 - X
d.test1 - -
a.test2 - -
b.test2 - X
c.test2 X -
d.test2 X X
Then I set up test1.runningipv6.net, test2.runningipv6.net up as my
search domains. (Info is still in there, feel free to try for
yourself. TTL is 20 seconds.) Results on my Mac running the latest
updates with both IPv4 and IPv6 connectivity:
(host talks directly to the DNS and looks for both A and AAAA)
$ host a
a.test1.runningipv6.net has address 192.0.2.101
a.test1.runningipv6.net has IPv6 address 2001:db8:1::a
$ host b
b.test1.runningipv6.net has IPv6 address 2001:db8:1::b
$ host c
c.test1.runningipv6.net has address 192.0.2.103
$ host d
d.test2.runningipv6.net has address 192.0.2.204
d.test2.runningipv6.net has IPv6 address 2001:db8:2::d
(traceroute only does IPv4)
$ traceroute a
traceroute to a.test1.runningipv6.net (192.0.2.101), 64 hops max, 40
byte packets
$ traceroute b
traceroute to b.test2.runningipv6.net (192.0.2.202), 64 hops max, 40
byte packets
$ traceroute c
traceroute to c.test1.runningipv6.net (192.0.2.103), 64 hops max, 40
byte packets
$ traceroute d
traceroute to d.test2.runningipv6.net (192.0.2.204), 64 hops max, 40
byte packets
(traceroute6 only does IPv6)
$ traceroute6 a
traceroute6 to a.test1.runningipv6.net (2001:db8:1::a) from
$ traceroute6 b
traceroute6 to b.test1.runningipv6.net (2001:db8:1::b) from
$ traceroute6 c
traceroute6 to c.test2.runningipv6.net (2001:db8:2::c) from
$ traceroute6 d
traceroute6 to d.test2.runningipv6.net (2001:db8:2::d) from
(telnet does both IPv4 and IPv6)
$ telnet a
Trying 2001:db8:1::a...
$ telnet b
Trying 2001:db8:1::b...
$ telnet c
Trying 2001:db8:2::c...
$ telnet d
Trying 2001:db8:2::d...
So your issue that the results are inconsistent is certainly real.
I'd say that the best way to avoid this is not having a search domain
at all, or at the very least not several. If someone wants to spend
time to come up with a reasonable guideline of how to behave that
gives the same results regardless of the type of connectivity that's
available, that would be good but probably extremely hard to do.
People like to use unqualified *and* partially qualified hostnames.
People also like to drive without seat belts. We don't let them do
that either... Or at least, we don't listen to their complaints when
the results are inferior to those obtained while driving _with_ a
seatbelt.
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