IPv6

• 10.220.147.178 versus 2002:0a00:0c18:0001:0000:0000:0000:0010

• IPv6 addresses are collapsible: 2002:a00:c18:1::10

• Specified as AAAA records in DNS (instead of IPv4's A records)
  Extra credit if you can figure out why...

• On operating systems with IPv6 enabled, try IPv6 first

• For each MX record, lookup AAAA records first then A records

• When probing interfaces, include IPv6 addresses in $=w if possible

• Can limit IPv4 or IPv6 usage via O DaemonPortOptions=Family= (DAEMON_OPTIONS()) (incoming connections) and O ClientPortOptions=Family= (confCLIENT_OPTIONS) (outgoing connections).

• Support bracketed IPv6 addresses (e.g., relay:[2002:a00:c18:1::10])

> nslookup
Default Server:  horsey.example.net
Address:  10.220.147.178

> set q=mx
> 6bone.net
6bone.net       preference = 0, mail exchanger = venera.isi.edu
> set q=aaaa
> venera.isi.edu
isi.edu
        origin = isi.edu
        mail addr = action.isi.edu
        serial = 2000022404
        refresh = 7200 (2H)
        retry   = 1800 (30M)
        expire  = 604800 (1W)
        minimum ttl = 86400 (1D)

> set q=a
> venera.isi.edu
Name:    venera.isi.edu
Address:  128.9.176.32
> set q=aaaa
> 6bone.net
6bone.net       IPv6 address = 2002:a00:c18:1::10