6

Result of dig -6 google.com:

; <<>> DiG 9.8.3-P1 <<>> -6 google.com
;; global options: +cmd
;; connection timed out; no servers could be reached

What does it means if dig -4 google.com works correctly? Does it mean that my provider doesn't support IPv6?

Update

My /etc/resolv.conf

#
# Mac OS X Notice
#
# This file is not used by the host name and address resolution
# or the DNS query routing mechanisms used by most processes on
# this Mac OS X system.
#
# This file is automatically generated.
#
nameserver 192.168.88.1

192.168.88.1 is my router

CAMOBAP
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  • What is in `/etc/resolv.conf`? – kasperd Aug 22 '16 at 20:47
  • @kasperd nothing specific there only one line `nameserver 192.168.88.1`, `192.168.88.1` is my router – CAMOBAP Aug 23 '16 at 06:21
  • You should add that information to your question, because without it no answer could be more than a guess. And if you do add it, the question will no longer be too broad. – kasperd Aug 23 '16 at 21:01

2 Answers2

15

-4/-6 tells dig to only use IPv4/IPv6 connectivity to carry your query to the nameserver - it doesn't change whether to query for A records(IPv4) or AAAA records(IPv6) if that's what you intended. If dig -4 works but dig -6 doesn't, it just means that your local nameserver can't be reached via IPv6, which can have various reasons. Sure, not having IPv6 connectivity is among them but it's unfortunately also common for some specific home routers to not act as a DNS forwarder on IPv6. They don't strictly need to, since your machine can use IPv4 to query for AAAA records.

If you want to quickly check if you can reach google.com via IPv6, you could do 

ping6 google.com
Rahul
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maxf
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    Also RAs don't carry DNS information. So afaict DNS over IPv6 requires either manual configuration or DHCPv6. – plugwash Aug 22 '16 at 19:09
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    @plugwash RA does support DNS: https://tools.ietf.org/html/rfc6106 – Ferrybig Aug 22 '16 at 20:17
  • Do major operating systems support that (relatively new) extension though? – plugwash Aug 22 '16 at 20:34
  • According to [this](https://discussions.apple.com/thread/6879615?start=0&tstart=0) thread at least OSX does. NetworkManager on Linux also seems to support it and Windows apparently doesn't. – maxf Aug 22 '16 at 20:42
10

Yes, that suggests that you do not have IPv6 connectivity.

If you want to obtain an IPv6 address for google rather than using IPv6 to obtain an address for google, you want

dig -t aaaa google.com

Use

ifconfig | grep inet6

to see if you have any global IPv6 addresses (that is, not ::1 and not any link local address beginning fe80::).

user4556274
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