[CentOS] IPv6 updating DNS

[Mark Tinberg]

On Wednesday, October 01, 2014 15:23:52 Mark Tinberg wrote:
> > > All of my servers and
> > > workstations are able to ping6 to outside targets, and anything with a
> > > browser installed can open ipv6.google.com.
> > >
> > > So far I have figured out that you have to run TWO instances of DHCP.  One
> > > instance issues IPv4 and the other issues IPv6.    I have not gone so far
> > > as to actually set up a second instance of DHCP.
> >
> > As long as you run a router advertisement daemon clients will self-assign
> > routable addresses, you don't really need DHCPv6 if you are also running
> > DHCPv4, you can set DNS (even an IPv6 DNS server) or any other
> > configuration using the DHCPv4 daemon.

> That is true - radvd does cause all my systems to self-assign a public IPv6
> address.  The problem is that radvd does NOT cause my DNS to get those
> addresses.  The result is I can use IPv6 internally only by giving the
> address.  I cannot use it by hostname.

> I suppose I could create static records in DNS.  Those self-assigned addresses
> are not going to change until I go on Google Fiber.  For that matter, I could
> use the FE80:: link-local addresses.  They are not routable, but I don't need
> that.  Being based on the MAC address, they won't change even when I move to
> Google Fiber.

I would create static AAAA(ddress) records using the FF:FE EUI64 self-assigned addresses as those are stable without any configuration required unlike DHCPv4 assigned addresses where dynamic updates or static MAC/IP configuration are needed.  If you allow it on your firewall you can also easily connect to services with public IPv6 addresses externally, if you get IPv6 when you are out and about (Verizon wireless is all IPv6 I think).

It might also be good to use Avahi mDNS/Zeroconf internally which will automatically pick up the addresses of your internal hosts without any configuration needed, which might be simpler than running DNS if you just have a single subnet and only care about the names locally.

> Still - it would be nice to have DNS automatically get IPv6 addresses just
> like DHCP does now for IPv4.

So is it correct to say that you currently have dynamic DNS configured between your DHCPv4 daemon and your DNS daemon so that DNS is automatically populated with A(ddress) records for your internal hosts with their RFC 1918 IPs.


—
Mark Tinberg
mark.tinberg at wisc.edu