Re: postfix for 2 domains on 1 vps 1 ip

[Bob Proulx <bob%proulx.com@localhost>]

Mayuresh wrote:
> I get 2 public ips from the cloud provider - one is ipv4 and one ipv6.
...
> Is this feasible?

But it's all "dual stack networking" these days.  Those two software
stacks, IPv4 and IPv6, are operated in parallel.  I strongly recommend
not to try to go with one logical virtual host having only IPv4 and
the other one only having only IPv6.  I think as a technical point
that it can be done that way but then there are other problems that
are worse because that is being attempted.  I strongly recommend not
to do it that way.  Operate them together as a dual stack network as
they are intended.  That is the middle of the road mainstream method.

Also note that we are at a transition point in time right now.  Where
right now is a window of time of a few years before now and after now.
We are transitioning from when IPv4 only was okay to when IPv6 is
required.  For example 99.44% (a number I use when I have no data but
feel it is overwhelming) of mail sites use IPv4.  Due to the long
history of using IPv4.  Due to the long problems of needing DNSBLs for
blocking spammers and scammers.  Which were all based upon IPv4.  For
many years most sites used *only* IPV4 due to spam problems of
enabling IPv6.  We are transitioning to a time when DNSBLs for IPv6
are fully useful in the same way.  Many will argue that we have
already passed that point in time and *only* IPv6 is needed already
and moving forward.  I am one of the hold-outs that only enable IPv4
for email at this moment but I know that must change at some point.

But for example my home ISP CenturyLink still to this very day does
not support IPv6 and only supports IPv4!  Wow!  Still today only IPv4.
And there are still others like that too.  But most providers and all
server level providers in datacenters will provide IPv6.  Even Amazon
is now finally providing IPv6 networking to their cloud nodes.  That
was a long, long time in coming.

My opinion is that for web servers they must have an IPv6 address
along with an IPv4 address.  They need to IPv4 for all of the older
iSPs like CenturyLink where client hosts like mine are stuck and only
have IPv4.  Therefore to browse the web the web must provide IPv4
addresses for poor souls like me stuck behind IPv4.  But mobile
clients such as phones and tablets on cell data networks many areas
are only getting IPv6 addresses.  Only getting IPv6 because there are
no spare IPv4 subnets available for those areas.  Many mobile data
client hosts have the opposite problem of needing IPv6 in order to
browse the web.  Therefore web servers should have both IPv4 and IPv6
addresses available.

Bob