Mailing List Message #9100
From: Elliot Wilen <>
Subject: Re: RBL+ subscription (feature request?)
Date: 05 Oct 2001 10:54:59 -0700
To: SIMS <>
X-Mailer: QuickMail Pro 1.5.4r2 (Mac)

Thanks very much for your reply. You're right--I obviously don't fully understand how DNS works. I'll do some more work based on your comments. Regarding a few items you brought up...

>Can you define what you mean by that? If you mean build a proper >recursive resolver into SIMS, that would be a bit much to handle the >pathological case of having nothing but MacDNS as a local nameserver.

What I was thinking of was including the option to have SIMS handle RBL lookups by directly determining the authoritative NS for the RBL domain and submitting its lookup to that NS.

I do agree that it's not worth doing anything to fix a problem caused solely by MacDNS.

>>seems that this should be too hard. For example, with WhatRoute,
>>when you do a name lookup, it seems to bypass the DNS servers listed
>>in TCP/IP and query the authoritative DNS server directly.
>No, it does not. Look at the options in WhatRoute: you can either >have it use the OT DNS config or you can specify alternate settings. >I don't believe it will do its own recursion though, since a correct >recursive resolver is significantly more complex to code than a >simple non-recursive one and there's little point to re-implementing >such a thing when you have one in the OS.

I came to my belief about WhatRoute through the fact that it was able to get replies to RBL+ queries when I ran it on the mail server, even when SIMS couldn't. Again, at that time, TCP/IP on the server had its DNS set to use the ISP's DNS servers.

>Incidentally, I suspect that your problem may well be MacDNS choking. >The MAPS zones return an extra TXT record, and I seem to recall that >going nuts when given one of those is one of MacDNS' known flaws.

I don't think so. I briefly tried setting MacDNS to use the MAPS NS as one of its parents and then putting the MacDNS server's IP as the first DNS server in TCP/IP. I *did not* have the MAPS NS listed among the DNS servers in TCP/IP. With this config, SIMS was able to use RBL+. But I realized that it would cause all my local users' DNS requests to be forwarded to the MAPS NS. Clearly not a thing to do.

To summarize, with SIMS, MacDNS, and WhatRoute running on same machine:

TCP/IP set to use ISP's DNS, MacDNS set to use ISP as parents: SIMS can't query RBL+, WhatRoute can.

TCP/IP set to use MAPS DNS, MacDNS set to use ISP as parents: SIMS works, didn't try WhatRoute.

TCP/IP set to use local MacDNS, MacDNS set to use MAPS as parent: SIMS works, didn't try WhatRoute.

--Elliot Wilen

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