IPv6 Connectivity Test

Ping
Use ping6 instead of ping

ping6 www.sixxs.net

IPv6 DNS Disablers
In order to prevent long time outs, some systems only return or store A (IPv4) records, not the AAAA (IPv6) records if there is no IPv6 connectivity.


 * Google does not return AAAA records unless you specifically registered your DNS query machine, and you can only register if you prove to have very good IPv6 support and have a significant user base.
 * Mac OS 10.5.5 and up does not cache AAAA records if you have no good IPv6 connectivity.

Mac OS X
Mac OS 10.4 and up does not cache AAAA records if you have no good IPv6 connectivity. For example, on my Mac:

% host www.sixxs.net www.sixxs.net is an alias for nginx.sixxs.net. nginx.sixxs.net has address 213.204.193.2 nginx.sixxs.net has IPv6 address 2001:960:800::2 % ping www.sixxs.net PING nginx.sixxs.net (213.204.193.2): 56 data bytes 64 bytes from 213.204.193.2: icmp_seq=0 ttl=57 time=18.659 ms % ping6 www.sixxs.net ping6: nodename nor servname provided, or not known

On Mac OS 10.5 and up, you can verify this behaviour by querying dnscacheutil: ~% dscacheutil -configuration DirectoryService Cache search policy: /Local/Default /BSD/local Settings: AAAA Queries - Disabled (link-local IPv6 addresses) Cache Cap    - 512 Default TTL  - 3600 Hash Slots   - 2048

Flush DNS Cache
You can explicitly flush your DNS cache.

On Mac OS up to 10.5.1:

lookupd -flushcache

On Mac OS 10.5.2 to 10.9:

dscacheutil -flushcache sudo killall -HUP mDNSResponder

Om Mac OS 10.10 and up:

discoveryutil udnsflushcaches

Now it should work fine:

% ping6 www.sixxs.net PING6(56=40+8+8 bytes) 2001:0DB8:767:fd:223:6cff:fe97:6ce6 --> 2001:960:800::2 16 bytes from 2001:960:800::2, icmp_seq=0 hlim=57 time=76.181 ms

An alternative is to configure lookupd to look for AAAA adresses in any case: sudo mkdir /etc/lookupd sudo echo 'AAAACutoff NO' >> /etc/lookupd/global