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Re: Ways to use DDNS with your own domain name (was Re: DynDNS no longer free.)

Chris Angelico grabbed a keyboard and wrote:
> On Fri, Apr 11, 2014 at 2:19 AM, David Guntner <david@guntner.com> wrote:
>> what you want to do is
>> create a CNAME record for the domain - set a CNAME of mydomain.org that
>> points to myhostname.someddns.com.
>> Presto!  Now when you try to access your home machine, you can simply
>> refer to mydomain.org and it will point you to the correct place.  You
>> can also set up CNAME records for subdomains (whatever.mydomain.org) to
>> point to your DDNS hostname as well.
> List newbie chiming in here, hope I'm not out of line!
> CNAMEs are immensely helpful, but they do have their limitations, so
> be careful. You can't, for instance, have a CNAME on mydomain.org and
> then also have an MX record on mydomain.org - so you'll have trouble
> receiving mail (unless DDNS lets you set an MX on
> myhostname.someddns.com, which I'm not sure about). You also can't
> have an SOA record, or any other type of record, on something that's
> CNAMEd elsewhere. Also, pointing a CNAME at another CNAME, while
> technically legal (I think), is potentially problematic - you may
> start seeing glitchiness with some clients, timeouts, etc.

Good points.  Within this particular context, I'm not sure that a SOA
record is that important, but it's worth noting.

You're right about the MX record.  By standards, a MX record should
always point to an A record and not a CNAME.  In practice, I'm not sure
it actually has an affect on anything.  I'm pretty sure, however, that
if pointing the MX to the CNAME doesn't work (or is problematic), you
can always point the MX to myhostname.someddns.com (which *is* an A
record) and your mail for the domain will still go there.  It's been so
long since I've had to do this that I can't remember if I did that or
just ignored the standard and pointed the MX at the CNAME anyway. :-)
But I do know that I had no problems getting mail sent to my domain and
Postfix handling it on the local Linux box.

> But as long as your needs are simple, that method will work very
> nicely. Among other benefits, you're free to move where your actual
> DDNS is hosted without anything changing - if you lose
> myhostname.someddns.com and replace it with
> myhostname.someotherddns.com, the only change you need to make is to
> your CNAME - everything that accesses mydomain.org will still work
> fine.
> I strongly recommend the practice. But do make sure you understand
> what you're doing.
> ChrisA


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