a bit of theory about PTR records requested

[Gregg Rosenberg]

I am not a DNS expert like others on this list.  Although I do manage DNS 
for well over 300 zones.

At 10:52 AM 03/29/2000, Steve Lee wrote:
>what is the difference between  A and the PTR  ?
>i can see that one does the opposite of of the other
>but what does the A and the PTR stand for?
>
>thanks.

In the forward zone you map host names to IP addresses using the "A" 
record.  Here is a more complete example forward zone.

; The @ tells bind to inherit the domain name from the named.conf or what 
ever you call your config file.
@               IN          SOA                        yourdomain.com. 
hostmaster.yourdomain.com. (
                                 2000031801            ; Serial number 
yyyymmddcc
                                 86400                 ; Refresh once a day
                                 3600                   ; Retry every hour
                                 604800               ; 604800 - Expire 
after a week
                                 86400 )               ; 86400 - Minimum 
TTL one day
;
; Declare your authoratative name servers that you told your domain 
registrar to use for this domain.
                 IN      NS      ns1.yourdomain.com.
                 IN      NS      ns2.yourdomain.com.
;
; Declare your primary and secondary mail servers.  You may run both 
yourself or have an ISP run the secondary.
                 IN      MX      10        mail.yourdomain.com.
                 IN      MX      20        mail.yourisp.net.
;
; Make the domain name respond to an IP address so that mail or other 
servers can authenticate you properly,
                IN      A       207.207.111.244

$ORIGIN yourdomain.com.
;
mail         IN      A            207.207.111.244
ftp         IN  A       207.207.111.245
;

Your ISP may or may not allow you to have your reverse or in-addr.arpa 
space deligated to you.
If you do manage your own or if you want to prepare the file to send to 
your ISP it would look as follows.

@            IN      SOA     111.207.207.in-addr.arpa. 
hostmaster.yourdomain.com.
(
                                 2000031801 ; Serial number yyyymmddcc
                                 86400           ; Refresh once a day
                                 3600             ; Retry every hour
                                 604800         ; 604800 - Expire after a week
                                 86400 )         ; 86400 - Minimum TTL one day

                 IN      NS      ns1.yourdomain.com.
                 IN      NS      ns2.yourdomain.com.
;
$ORIGIN 111.207.207.IN-ADDR.ARPA.

244         IN      PTR     mail.yourdomain.com.
245         IN      PTR     ftp.yourdomain.com.

I hope this helps those that need to know some aspects of the basics on 
this list.  For those in the know, we were all there place, so pardon the 
use of bandwidth to help others.
--
Gregg Rosenberg -- N9NNO
RICIS, Inc.
gregg at ricis.com

"Obstacles are those frightful things you see when you
take your eyes off your goals."  Author unknown