[Pdns-users] Creating a www CNAME in powerDNS Admin (mysql backend) automatically pointing to @

[Andrea Biancalani]

Seems pretty clear now.

I'm not interested into making redirect visible in public queries, so I 
suppose I'll go for the most standard one

> @ SOA ...
> @ NS ...
> @ MX ...
> @ ALIAS /*webhost.servername.tld.*//**/
> www A 192.0.2.1
> www AAAA 2001:db8::1

considering that this dns server is authoritative for 
/*webhost.servername.tld*/ it seems the simplest way to achieve my goal 
to standardize a template for any new domain with same structure.

Many thanks for your time Brian, very appreciated!

Andrea


Il 23/01/2023 13:21, Brian Candler ha scritto:
> On 23/01/2023 12:10, Andrea Biancalani wrote:
>>
>> my default template for new hosting is similar to this
>>
>>> @ SOA ...
>>> @ NS ...
>>> @ MX ...
>>> @ A 192.0.2.1
>>> @ AAAA 2001:db8::1
>>> www A 192.0.2.1
>>> www AAAA 2001:db8::1
>>
>> but if I try to use this template
>>
>>> @ SOA ...
>>> @ NS ...
>>> @ MX ...
>>> @ ALIAS www. /*(added final dot)*/
>>> www A 192.0.2.1
>>> www AAAA 2001:db8::1
>>
>> I can resolve the www.foo.bar record, but when trying to resolve 
>> foo.bar I get a "Server failed" answer ( dns-server is not able to 
>> find foo.bar)
>
> That is as expected. If you add the final dot to www, then you are 
> forcing it to resolve the top-level name, literally just "www" (not 
> "www.foo.bar"), which of course does not exist.
>
> If this were a BIND zonefile, then "www" without the dot would have 
> the current domain appended implicitly.  I haven't tried this with PDNS.
>
> Also, alias records only work if you've configured pdns-auth with a 
> resolver to be able to look them up.
>
>
>>
>> Trying to use a template like this instead, gave as result a "RRset 
>> foo.bar. IN CNAME: Conflicts with pre-existing RRset"
>>
>>> @ SOA ...
>>> @ NS ...
>>> @ MX ...
>>> @ CNAME www. /*(added final dot)*/
>>> www A 192.0.2.1
>>> www AAAA 2001:db8::1
>>
> That is forbidden by the RFCs. A CNAME cannot exist at the same 
> position in the DNS tree as any other records: in your case above, you 
> have SOA, NS and MX records with the same label, which conflict with it.
>
>
>> that doesn't happens if I use the zone record as target of the CNAME
>>
>>> @ SOA ...
>>> @ NS ...
>>> @ MX ...
>>> @ CNAME foo.bar. /*(added final dot)*/
>>> www A 192.0.2.1
>>> www AAAA 2001:db8::1
>
> That should give the same error - it doesn't make any difference what 
> the target of the CNAME is - except if the domain in question is 
> foo.bar, then you have a CNAME from foo.bar pointing to foo.bar, which 
> is meaningless anyway. It may have been silently discarded.
>
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