DNS hostnames with a duplicate CNAME and A record - which should be removed?

jeff weisberg jaw+nanog01 at tcp4me.com
Thu Oct 18 15:49:31 UTC 2012

On 17 Oct 2012, at 15:25, Landon Stewart wrote:

> The problem is that we have some zones that have records with the same
> hostname that have both a CNAME as well as an A record, MX record, SOA
> record and/or NS record.

> # dig @ns1.superb.net +nocmd superbcolo.biz mx +noques +answer
> superbcolo.biz. 86400 IN MX 10 superbcolo.biz.
> superbcolo.biz. 86400 IN CNAME superbenterprise.net.

> Should the CNAME just get nuked in all of these cases?


if you nuke them, you'll break something.

you're going to need to go through them all one by one, figure out
why the CNAME is there, what it is doing, and how to change it.

for example, "superbcolo.biz" has an MX and CNAME. the CNAME
points to "superbenterprise.net", which has an A, and that A
has a web server running.

it may be "wrong", but http://superbcolo.biz works. so in this
case, you'd need to replace the CNAME with the A. otherwise,
you're breaking someone's website. which might be bad.

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