reverse lookup to CNAME

[Matus UHLAR - fantomas]

> On Sat, Jan 24, 2009 at 9:21 PM, Matus UHLAR - fantomas
> <uhlar at fantomas.sk> wrote:
> >
> > if metis.local is a CNAME, the PTR shouldn't point to it.

On 25.01.09 10:14, John Bond wrote:
> could you please explain this.

Although it's good to remove irelevant part of the text you are replying to,
this time you removed the relevant part. I'm pasting below...

>  When i tried this host did not resolve
> the cname.  i.e a host 1.1.1.1 returned metis.local.  it did not know
> to resolve metis.local as bob....

the host 1.1.1.1 returned that 1.1.1.1.in-addr.arpa is a CNAME to
metis.local. It's not reverse record, the PTR is, and metis.local has no
PTR. Even if it did, the PTR should be on 1.1.1.1.in-addr.arpa, you are
putting one more unnecessary step into resolution.

[pasted relevant text]
> > bob-www-sol-l01     IN           A          1.1.1.1
> > metis                    IN           CNAME bob-www-sol-l01
> >
> > zone for 1.1.1
> >
> > 1                         IN           CNAME  metis.local.


On 23.01.09 23:06, Barry Margolin wrote:
> Why don't you just use normal reverse DNS:
>
> zone for 1.1.1.in-addr.arpa
>
> 1 IN PTR metis.local.
>   IN PTR bob-www-sol-l01.local.

accorging to the above, metis.local is a CNAME, so the reverse should point
to bob-www-sol-l01.local. - pointing it to metis.local. would be incorrect.
And although two or PTRs usually make no problems, it's recommended not to
do that, because some SWs jsut can't handle that (even if they would all be
correct). So, keep only PTR to bob-www-sol-l01.local.

-- 
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