question about reverse lookup

[Brad Knowles]

At 11:43 PM +0000 9/20/01, Barry Margolin wrote:

>  These errors are wrong.  There are three PTR records for that address, and
>  they all point to hostnames that resolve to that address:
>
>  10.84.14.12.in-addr.arpa.  23h3m7s IN CNAME  10.0/26.84.14.12.in-addr.arpa.
>  10.0/26.84.14.12.in-addr.arpa.  23h59m47s IN PTR  wss3.na.bestfoods.com.
>  10.0/26.84.14.12.in-addr.arpa.  23h59m47s IN PTR  na.bestfoods.com.
>  10.0/26.84.14.12.in-addr.arpa.  23h59m47s IN PTR  www.prodmaiz.com.

	Yup.  This is a clear example where multiple PTR records are not 
handled properly by a program, in this case a DNS debugging tool. 
That said, I don't know of any other DNS debugging tools that 
validate reverse DNS records that would handle this situation 
properly.

>  Neither of the above is a problem with the bestfoods.com domain, they're a
>  problem with the reverse DNS for the web hosting site that happens to be
>  hosting their web server.  But since there's no requirement for their web
>  server to have valid reverse DNS, this is inconsequential.

	No, they don't have to have valid reverse DNS, but if they're 
going to have it, they most certainly should have it done properly 
and without lame delegations.  I view this as a clear problem, 
although perhaps not one that would cause the mail problems seen by 
the original poster.

>  I'm not even sure why it cares about this reverse domain.  None of the
>  other messages mention any addresses in this range.

	Dunno.  I'm working on trying to figure out where those addresses 
came from.  I do note that in a transfer of the entire zone, the 
www2.bestfoods.com address comes up in this range:

% dig @dbru.br.ns.els-gms.att.net. bestfoods.com. axfr

; <<>> DiG 9.2.0rc3 <<>> @dbru.br.ns.els-gms.att.net. bestfoods.com. axfr
;; global options:  printcmd
bestfoods.com.          86400   IN      SOA 
dbru.br.ns.els-gms.att.net. rm-hostmaster.ems.att.com. 16 86400 10000 
600000 86400
bestfoods.com.          86400   IN      NS      dbru.br.ns.els-gms.att.net.
bestfoods.com.          86400   IN      NS      dmtu.mt.ns.els-gms.att.net.
brands.bestfoods.com.   86400   IN      MX      30 smtp3.san.cerf.net.
brands.bestfoods.com.   86400   IN      MX      10 brands.bestfoods.com.
brands.bestfoods.com.   86400   IN      MX      20 mail1.ruppman.com.
brands.bestfoods.com.   86400   IN      A       199.248.129.23
nordic.bestfoods.com.   86400   IN      A       194.52.178.236
www.nordic.bestfoods.com. 86400 IN      A       194.52.178.236
na.bestfoods.com.       86400   IN      A       12.14.84.10
na.bestfoods.com.       86400   IN      MX      10 wss3.na.bestfoods.com.
wss3.na.bestfoods.com.  86400   IN      A       12.14.84.10
baking.bestfoods.com.   86400   IN      MX      10 smtp.gwbakeries.com.
as.bestfoods.com.       86400   IN      MX      10 wss3.na.bestfoods.com.
www.stars.bestfoods.com. 86400  IN      A       199.170.229.246
eu.bestfoods.com.       86400   IN      MX      100 mail01.unilever.com.
eu.bestfoods.com.       86400   IN      MX      100 mail02.unilever.com.
eu.bestfoods.com.       86400   IN      MX      100 mail04.unilever.com.
www.bestfoods.com.      86400   IN      A       199.248.129.22
asia.bestfoods.com.     86400   IN      MX      100 wss3.na.bestfoods.com.
wss2.asia.bestfoods.com. 86400  IN      A       168.70.234.126
wss1.asia.bestfoods.com. 86400  IN      A       168.70.234.97
www2.bestfoods.com.     86400   IN      A       216.175.185.211
la.bestfoods.com.       86400   IN      MX      10 wss3.na.bestfoods.com.
bestfoods.com.          86400   IN      SOA 
dbru.br.ns.els-gms.att.net. rm-hostmaster.ems.att.com. 16 86400 10000 
600000 86400
;; Query time: 398 msec
;; SERVER: 199.191.128.106#53(dbru.br.ns.els-gms.att.net.)
;; WHEN: Thu Sep 20 20:14:24 2001
;; XFR size: 26 records

-- 
Brad Knowles, <brad.knowles at skynet.be>

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