[Coco] yahoo groups

[John E. Malmberg]

Kevin Diggs wrote:
>>
> rDNS? What is rDNS? Is it like a reverse DNS name resolution? 

It is reverse DNS name resolution.  Also known as PTR records.

>Is there a *nix utility to find it?

bash$ host 206.40.45.151
151.45.40.206.in-addr.arpa domain name pointer dialpw151.hypersurf.com.

Or you can use NSLOOKUP or DIG after manually converting the address to 
in-addr.arpa notation.

Each "subnet" of the reverse notation is delegated to specific name 
servers for resolution.  That is why the rDNS address can not be forged.

In this case, DIG shows the DNS servers that can answer for the 256 I.P. 
addresses for the subnet.

bash$ dig 151.45.40.206.in-addr.arpa

; <<>> DiG 9.2.4 <<>> 151.45.40.206.in-addr.arpa
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 65387
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;151.45.40.206.in-addr.arpa.    IN      A

;; AUTHORITY SECTION:
45.40.206.in-addr.arpa. 86366   IN      SOA     mercury.hypersurf.com. 
surfmaster.hypersurf.com. 2000101200 172800 3600 1728000 172800

;; Query time: 78 msec
;; SERVER: 10.16.0.30#53(10.16.0.30)
;; WHEN: Sat Apr 21 22:36:32 2007
;; MSG SIZE  rcvd: 112

-John
wb8tyw(at)qsl.net
Personal Opinion Only