A And Cname-record

[Mark Andrews]

> On 18 Jun 2020, at 07:56, Bogdan-Stefan Rotariu <bogdan at rotariu.ro> wrote:
> 
> Hi,
> 
>> On 18 Jun 2020, at 00:44, Ejaz Ahmed <mejaz at cyberia.net.sa> wrote:
>> 
>> when i am trying to add A and CNAME record together  for the same subdomain, getting an error as below, you all kind  assistance would be highly appreciated thanks in  advance
>> 
>> my records are as follows in zone 
>> 
>> auotdiscover IN A 1.1.1.1
>> autodiscover IN CNAME autodiscover.acig.com.sa
>> 
>> ======================================================
>> dns_master_load: acig.com.sa.hosts:102: autodiscover.acig.com.sa: CNAME and other data
>> 
>> zone acig.com.sa/IN: loading from master file acig.com.sa.hosts failed: CNAME and other data
>> 
>> zone acig.com.sa/IN: not loaded due to errors 
> 
> CNAME records cannot coexist with any other records last time I’ve checked. See section 2.4 from RFC1912[1]
> 
> [1] https://tools.ietf.org/html/rfc1912

Well it actually goes back to RFC 1034.  Unfortunately it wasn’t enforced in
nameservers at the beginning and is still not enforced by some servers.

3.6.2. Aliases and canonical names

...

The domain system provides such a feature using the canonical name
(CNAME) RR.  A CNAME RR identifies its owner name as an alias, and
specifies the corresponding canonical name in the RDATA section of the
RR.  If a CNAME RR is present at a node, no other data should be
present; this ensures that the data for a canonical name and its aliases
cannot be different.  This rule also insures that a cached CNAME can be
used without checking with an authoritative server for other RR types.

Mark

> —
> Bogdan-Stefan Rotariu
> 
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742              INTERNET: marka at isc.org