RE: Reverse DNS Lookup...

[Jim Langston <jlangston@xxxxxxxxxxx>]

DNS entries for machines have an MX and an A record.

The MX stands for Mail Exchange.  Not sure what the A
records stands for.  One converts from the name to the
IP address, once converts from the IP address to the
name.

If you can not do a reverse DNS lookup on specific
hosts, I would suspect they are missing one of these
records (I believe the A records is IP to Name).

Try other IP addresses that you know have both records.
Here's a good example.  In windows go to a DOS prompt.
type:
ping www.midrage.com
that tells us the IP address is 63.167.147.106.
then type:
ping -a 63.167.147.106
No name comes back.  Looks like David doesn't have an
'A' record for his DNS entry.

If we do the same for www.microsoft.com:
ping www.microsoft.com (207.46.197.101)
ping -a 207.46.197.101 (microsoft.com)

Microsoft does have an 'A' record associated with it's
DNS entry.

Sorry for showing this in PC commands, not positive what
the AS/400 commands are (and my AS/400 isn't connected to
the internet anyway).

Regards,

Jim Langston


-----Original Message-----
From: Scott Klement [mailto:klemscot@klements.com]
Sent: Tuesday, December 04, 2001 3:53 PM
To: rpg400-l@midrange.com
Subject: RE: Reverse DNS Lookup...



I can't do reverse lookup on your "www.ctlaltdel.org" either.  Not with
the program, not with the UNIX "host" command, not with the NSLOOKUP
command...   it does not appear to have reverse DNS associated with it.

The 216.115.108.245 does work from my AS/400, however.

The other example (the one that you originally posted) is one that I would
never use in production :)   It may work some of the time, but it surely
will also fail some of the time.   Really.  Use the one that I posted, or
another one that's written correctly :)


On Tue, 4 Dec 2001, Andrew Borts wrote:

> OK - Cut & pasted your results. Compiled (it compiled on the first time
> - stop showing off!) and I still get blanks returned.  I even tried
> using the example that Peter gave of 216.115.108.245 to do my lookup
> instead of my home server (www.ctlaltdel.org ) and STILL got blanks.
>
> I'm leaning toward setting up the DNS server on my AS/400 @ home, and
> trying the code there...
>
>
> Andrew Borts / Webmaster