[systemd-devel] networkd failure with ipv6.disable=1

["Jóhann B. Guðmundsson"]

On 05/11/2015 10:31 AM, Andrei Borzenkov wrote:
> I had issues with accessing some sites with IPv6 enabled. Not everyone
> lives in shiny new world and IPv6 support from providers can be quite
> buggy.

Most likely due to misbehaving name servers which should then be 
reported to hostmaster of the site.

If you disables IPv6 support in the kernel it only prevents the relevant 
network interfaces from being created, it does not result in disabling 
IPv6 name lookups from programs that makes an AF_UNSPEC or AF_INET6 
request afaik hence you always end up double query the name servers ( 
with all it's downside ) unless you disable that within the application 
itself hence disabling ipv6 in the kernel makes little to no sense.

You can alleviate the downside of double lookups by adding "options 
single-request" or "options single-request-reopen" ( the latter probably 
solves most of the issues with misbehaving name servers ) to 
/etc/resolv.conf but afaik you cannot disable globally ipv6 lookups for 
all applications that perform it.

JBG