svn commit: r239356 - head/sbin/dhclient

[Hajimu UMEMOTO]

Hi,

>>>>> On Wed, 22 Aug 2012 04:06:46 +0400
>>>>> Andrey Chernov <ache at FreeBSD.ORG> said:

ache> BTW, I notice that link-local router address behavior is 
ache> strange and inconsistant for both 'host -6' and 'dig -6' commands.
ache> host -6 example.com fe80::<rest of router address>
ache> dig -6 @fe80::<rest of router address> example.com
ache> both hangs, but in the same time
ache> host -6 example.com fe80::<rest of router address>%<iface>
ache> dig -6 @fe80::<rest of router address>%<iface> example.com
ache> works!
ache> host -6 example.com fe80::<rest of router address>%1
ache> dig -6 #fe80::<rest of router address>%1 example.com
ache> works too. Not understanding addresses without %<iface> or %1 looks like 
ache> routing problems, but I don't know where to fix it.

A link-local address has a scope; an interface here.  You cannot omit
it on FreeBSD by default.  To be able to omit it, specify something
like ipv6_default_interface="em0" in your /etc/rc.conf.

ache> So, I try to use 
ache> nameserver fe80::<rest of router address>%<iface> (or with %1 suffix)
ache> in my resolv.conf, as result
ache> host -6 example.com
ache> dig -6 example.com
ache> (without NS specified) both hangs despite they working when exact the same 
ache> NS address is given in their command lines.

Our stub resolver in libc should work with a link-local address as
nameserver.  However, host(1) and dig(1) don't use the stub resolver
in libc, and use its own resolver.  I suspect host(1) and dig(1) have
some problem in handling a link-local address.
In anyway, I don't recommend to use a link-local address for DNS.

Sincerely,

--
Hajimu UMEMOTO
ume at mahoroba.org  ume@{,jp.}FreeBSD.org
http://www.mahoroba.org/~ume/