# IPv4/IPv6 preference



## Abacus (Jul 7, 2010)

Hi there,

I've been Googling this for about 20 minutes and haven't found anything relevant. On Linux, the configuration file gai.conf allows me to set getaddrinfo() to prefer AAAA records over A records when doing a DNS lookup. I can't find an equivalent on FreeBSD.

All I found was this page, which says "FreeBSD prefers IPv6 if a DNS query results in IPv4 and IPv6 addresses being sent back (A and AAAA RRs)". This doesn't seem to be the case.

I know for certain that v4v6.ipv6-test.com does have both AAAA and A records, but FreeBSD is preferring to connect via IPv4. When I put an IPv6-only address into my browser (v6.ipv6-test.com), FreeBSD does connect over IPv6 as it should (so I know for certain that both IPv6 and IPv4 are working fine, it's just a matter of preferring one over the other in a DNS lookup).

Any ideas?


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## aragon (Jul 8, 2010)

ip6addrctl(8)
http://tools.ietf.org/html/rfc3484


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## Abacus (Jul 8, 2010)

Perfect. Thank you.


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## athei (Oct 6, 2014)

Just used this to make IPv6 default in FreeBSD10.0. Do these changes survive reboot?


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## SirDice (Oct 6, 2014)

Add to /etc/rc.conf:

```
ip6addrctl_enable="YES" # Set to YES to enable default address selection
ip6addrctl_verbose="NO" # Set to YES to enable verbose configuration messages
ip6addrctl_policy="AUTO"        # A pre-defined address selection policy
                                            # (ipv4_prefer, ipv6_prefer, or AUTO)
```


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