PTR records

[Joseph S D Yao]

On Wed, Sep 27, 2000 at 07:17:39PM -0400, Michele Chubirka wrote:
> The CNAME record is for that purpose. Why does it show up as an error if a
> DNS database has multiple A records for one IP address in most DNS
> diagnostic tools? Why even have CNAME records. While Bind may still work,
> the RFCs still seem to imply that it's cleaner to use one A name per IP and
> CNAMES referring to the A record.

Again, there are certain times when you MAY NOT use CNAME records.
When there is another record for the same name (e.g., SOA, NS, MX).
When it is an NS or MX record target.

Why have CNAMEs?  Single-stop changes.  Instead of having to stop at
each use of the name and decide whether it should be changed.  I could
have two sets of names:

	franklin	IN A		...
	mail		IN CNAME	franklin
	pop3		IN CNAME	franklin
	mailhost	IN CNAME	franklin
	...

	arachne		IN A		(same)
	web		IN CNAME	arachne
	www		IN CNAME	arachne
	...

and if I move the Web server to another host, or the mail server to
another host, I don't have to change all the aliases that somebody or
another just felt they had to have.

-- 
Joe Yao				jsdy at cospo.osis.gov - Joseph S. D. Yao
COSPO/OSIS Computer Support					EMT-B
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