Parent is a CNAME

Joseph S D Yao jsdy at
Wed Dec 2 03:50:29 UTC 2009

On Tue, Dec 01, 2009 at 04:59:16PM -0800, Hans Jacobsen wrote:
> If is a cname (say to
> can I delegate  Are there documents that  
> point to this being an ok or bad practice?
> I know all records for are relegated to records for  
> What about subdomains?


The domain that has a CNAME must never appear on the left-hand side of
another record.

If you delegate, the domain appears on the left side of NS records.

If you include the domain in a declaration in the same zone, it still is
on the left side of a record - just not alone.

a			CNAME		b
; Delegate a - WRONG
a			NS		ns1		[WRONG]
; Use a on LHS - WRONG
subdomain.a		A	[WRONG]
subdomain.a		NS		ns1.subdomain.a	[WRONG]
ns1.subdomain.a		A	[WRONG]

Why not do this?

subdomain.b		A
subdomain.b		NS		ns1.subdomain.b
ns1.subdomain.b		A

** Joe Yao				jsdy at - Joseph S. D. Yao

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