I need to create an NS record for a domain that is a CNAME, for the purpose of having two domains pointed at one IP, and not having to maintain the current IP address in two different places.

The DNS provider for this domain is DynDNS, but they block this operation:

CNAME cannot be created with label that is equal to zone name

I can do this with another domain whose DNS is served by 1and1:

root@srv-ubuntu:~# dig myseconddomain.co.uk

; <<>> DiG 9.4.2-P1 <<>> myseconddomain.co.uk
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61795
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;myseconddomain.co.uk.             IN      A

myseconddomain.co.uk.      71605   IN      CNAME   myfirstdomain.co.uk.
myfirstdomain.co.uk.     59      IN      A       www.xxx.yyy.zzz

;; Query time: 298 msec
;; WHEN: Tue Aug 18 14:17:26 2009
;; MSG SIZE  rcvd: 78

Is this a breach of the RFCs or does DynDNS have a legitimate reason for blocking this action?

Followup Thanks to the two answers already posted I now know that 1and1 IS breaching RFCs to do this. However it does work and they seem to support it. For a company that hosts so many domains it seems very odd that they get away with doing this on such a massive scale without objection.

More followup

The output of "dig myseconddomain.co.uk ns" as requested.

root@srv-ubuntu:~# dig myseconddomain.co.uk ns

; <<>> DiG 9.4.2-P1 <<>> myseconddomain.co.uk ns
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 18085
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 2

; myseconddomain.co.uk.             IN      NS

myseconddomain.co.uk.      4798    IN      NS      ns67.1and1.co.uk.
myseconddomain.co.uk.      4798    IN      NS      ns68.1and1.co.uk.

ns67.1and1.co.uk.       78798   IN      A
ns68.1and1.co.uk.       86400   IN      A

;; Query time: 59 msec
;; WHEN: Wed Aug 19 12:54:58 2009
;; MSG SIZE  rcvd: 111

5 Answers 5


Correct, it is a breach of RFC 1034, section 3.6.2, paragraph 3:

... 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 applies here because the root of your zone must also have SOA and NS records.

  • This answers the original question, so thanks for that. I would appreciate any insight you have on the followup I posted in the question.
    – tomfanning
    Commented Aug 18, 2009 at 14:13
  • It would be possible for your domain to have a CNAME record if the provider can accommodate entering the CNAME into the parent zone, and not its own zone, although it would not have its own SOA or NS records in that case.
    – mark4o
    Commented Aug 18, 2009 at 14:26
  • Is that what you see in the "dig" query I made in the question? (I'm no DNS expert, just enough to get by...)
    – tomfanning
    Commented Aug 18, 2009 at 14:37
  • That dig query does not request SOA or NS records. Try: dig myseconddomain.co.uk ns
    – mark4o
    Commented Aug 18, 2009 at 14:58
  • I have updated my answer with the results from your query.
    – tomfanning
    Commented Aug 19, 2009 at 11:56

Use the DynDNS WebHop service. This is free for their DNS customers.

It allows you to redirect traffic for the second domain to the first one, and not break any RFCs.

The redirect is a 302 (temporary) one, so it may harm some search engine rankings. (I suspect this could also be a problem with CNAME records.) See the above link for more information.


Yes, there is breach on the RFC for that. Check this explanation . I think is possible but not fully compliant with the RFC.

  • This link has gone stale.
    – sysadmin1138
    Commented Jan 12, 2021 at 17:07

The cname would be invalid and can cause problems down the road. The work around is to use the apache alias or rewrite modules to redirect the traffic. Check out this post explaining how to do this in apache. Migrating one domain to another


Yes, it does normally break the DNS standard when creating a CNAME record at the root/apex, however some DNS providers have implemented workarounds:

  • Cloudflare provide excellent free DNS hosting with a feature called "CNAME Flattening" whereby you can add a CNAME at the root of your zone but Cloudflare servers will actually return the resolved A/AAAA records to queries, thereby not breaking the standard
  • DNSMadeEasy also offer a similar thing, referred to as "ANAME" records
  • DNSimple also offer this via "ALIAS" records
  • easyDNS also offers ANAME records
  • PointDNS also offers ALIAS records

I'm a happy Cloudflare customer, and have found their solution to work really well.

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