My subdomains for clifford.org.uk are set up as cnames (www, potpourri, 
rp).

I should like clifford.org.uk to redirect to www.clifford.org.uk.  I have 
set up the redirection index.http as suggested in the A&A's help pages but 
I assume I need dns as well.  I can't use a CNAME can I.  Do I set up an A 
record for clifford.org.uk?


-- 
Alan

( If replying by mail, please note that all "sardines" are canned.
   However, unless this a very old message, a "tuna" will swim right
   through. )

On Sun, 2009-09-20 at 13:54 +0100, Alan Clifford wrote:
> 
> My subdomains for clifford.org.uk are set up as cnames (www, potpourri, 
> rp).
> 
> I should like clifford.org.uk to redirect to www.clifford.org.uk.  I have 
> set up the redirection index.http as suggested in the A&A's help pages but 
> I assume I need dns as well.  I can't use a CNAME can I. 

No, you can't. Since you have an MX record for clifford.org.uk, I'm
guessing you use that for mail -- and you mustn't ever have a CNAME for
domain names which are used in email (not even if you did want your
email to be delivered to the host which the CNAME points to -- that's
invalid).

>  Do I set up an A record for clifford.org.uk?

Yes, you'll need to set its A and AAAA records to match those of
a.www-server.co.uk.

This is a bit of a PITA, because you have to keep track of any IP
address changes -- you can't just rely on the fact that A&A will change
the A&AAAA records of a.www-server.co.uk, as you could if you were using
CNAMEs. But I'm not aware of any better option.

Using SRV records for http would work in theory, but I don't think
anyone ever actually honours them.

-- 
dwmw2

On Sun, 20 Sep 2009 08:15:25 -0700, David Woodhouse 
wrote:

> On Sun, 2009-09-20 at 13:54 +0100, Alan Clifford wrote:
>>
>> My subdomains for clifford.org.uk are set up as cnames (www, potpourri, 
>> rp).
>>
>> I should like clifford.org.uk to redirect to www.clifford.org.uk.  I have 
>> set up the redirection index.http as suggested in the A&A's help pages but 
>> I assume I need dns as well.  I can't use a CNAME can I. 
>
> No, you can't. Since you have an MX record for clifford.org.uk, I'm
> guessing you use that for mail -- and you mustn't ever have a CNAME for
> domain names which are used in email (not even if you did want your
> email to be delivered to the host which the CNAME points to -- that's
> invalid).

Sorry but I don't see that; clifford.org.uk has an MX address (whose value
is A.secondary-mx.co.uk) but clifford.org.uk is not the value of any MX
address, which is the important point.  I'd say CNAME would work just fine.

Tony

Anthony R. Gold  wrote:
> On Sun, 20 Sep 2009 08:15:25 -0700, David Woodhouse 
> wrote:
> 
>> On Sun, 2009-09-20 at 13:54 +0100, Alan Clifford wrote:
>>>
>>> My subdomains for clifford.org.uk are set up as cnames (www, potpourri, 
>>> rp).
>>>
>>> I should like clifford.org.uk to redirect to www.clifford.org.uk.  I have 
>>> set up the redirection index.http as suggested in the A&A's help pages but 
>>> I assume I need dns as well.  I can't use a CNAME can I. 
>>
>> No, you can't. Since you have an MX record for clifford.org.uk, I'm
>> guessing you use that for mail -- and you mustn't ever have a CNAME for
>> domain names which are used in email (not even if you did want your
>> email to be delivered to the host which the CNAME points to -- that's
>> invalid).

It wouldn't be possible even if there was no MX record, since the
CNAME would still clash with the NS records (see below).

> Sorry but I don't see that; clifford.org.uk has an MX address (whose value
> is A.secondary-mx.co.uk) but clifford.org.uk is not the value of any MX
> address, which is the important point.  I'd say CNAME would work just fine.

No, this is completely back to front. There's no reason that the value
of an MX record cannot be a CNAME (although one may wish to avoid it for
efficiency reasons), but you cannot have a CNAME for a name that has
*any* other record. That includes NS records, which are going to be
required for the domain to work at all, and MX records, likely to be
required for mail for the domain to work.

The OP needs an A record pointing to his web server.

See RFC 1912 sec 2.4[1]

[1] http://tools.ietf.org/html/rfc1912

-- 
Dominic Hargreaves | http://www.larted.org.uk/~dom/
PGP key 5178E2A5 from the.earth.li (keyserver,web,email)

On Sun, 20 Sep 2009, Anthony R. Gold wrote:

>> On Sun, 2009-09-20 at 13:54 +0100, Alan Clifford wrote:
>>>
>>> I should like clifford.org.uk to redirect to www.clifford.org.uk.  I have
>>> set up the redirection index.http as suggested in the A&A's help pages but
>>> I assume I need dns as well.  I can't use a CNAME can I.
>>
>> No, you can't. Since you have an MX record for clifford.org.uk, I'm
>> guessing you use that for mail -- and you mustn't ever have a CNAME for
>> domain names which are used in email (not even if you did want your
>> email to be delivered to the host which the CNAME points to -- that's
>> invalid).
>
> Sorry but I don't see that; clifford.org.uk has an MX address (whose value
> is A.secondary-mx.co.uk) but clifford.org.uk is not the value of any MX
> address, which is the important point.  I'd say CNAME would work just fine.
>
> Tony
>

Thanks guys.  I've been worrying, and searching, about the CNAME ban on MX 
since my first post. Since I don't actually have an A record either, my 
logic was a bit out on this one I think.

Trying the CNAME now.  I don't actually use mail on this domain so I won't 
be risking breaking it in the short term.  I might be using it in the 
future though so I don't want to do anything wrong.

-- 
Alan

( If replying by mail, please note that all "sardines" are canned.
   However, unless this a very old message, a "tuna" will swim right
   through. )

On Sun, 20 Sep 2009, Dominic Hargreaves wrote:

>
> It wouldn't be possible even if there was no MX record, since the
> CNAME would still clash with the NS records (see below).
>

Oh yes.  Oops!

>
> The OP needs an A record pointing to his web server.
>

Looks like it.

> See RFC 1912 sec 2.4[1]
>
> [1] http://tools.ietf.org/html/rfc1912
>

They make it quite clear there.

Thanks.

-- 
Alan

( If replying by mail, please note that all "sardines" are canned.
   However, unless this a very old message, a "tuna" will swim right
   through. )

On 20 Sep 2009, David Woodhouse verbalised:
> This is a bit of a PITA, because you have to keep track of any IP
> address changes

How often do these happen? I've got quite a lot of systems out there on
the net which (for reasons much too horrible to go into) allow me in via
IP-address-based ACLs (as well as challenge-response authentication
behind that). It takes weeks to regain access to all these systems
whenever my IP address changes and I have to bother quite a few people
with transatlantic phone calls (and one to Australia where the timezones
are against me as well).

Thankfully it hardly ever changes: in fact I can recall only one change
in the last fifteen years which wasn't correlated with a change of ISP
(that being the Zetnet implosion this year).