Is the diagnostic provided by DNScog reliable?

I have read other posts where people are mystified by the ressults of DNScog testing.

In my case, one glaring example is that DNScog claims it cannot send mail to "postmaster," yet everyone else in the world can.

Once one gets one result which is absolutely false, then one questions the reliability of the entire test.

asked Dec 30 '10 at 02:55 PM in Default

WHMagill
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4 answers:

I only experience problems with these two mail related DNSCog tests:

Check for valid MX records with unique IP address and
Check SPF record

The problem being that DNSCog believes I have duplicate MX and SPF records.

I have no problems with the postmaster@ or abuse@ tests. If you click "View Details", what does it say?

answered Dec 30 '10 at 03:06 PM

VikingTiger ♦
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WHMagill Dec 31 '10 at 08:10 PM

pacecat.mcgillsociety.net. 98.140.106.69: rcpt_to_postmaster --

I.e. it says nothing other than what it says in prose. If one asumes that the underscore "_" is meant to represent a space, and then assume that "rcpt to postmaster" represents the SMPT command being issued, then clearly the test will fail as THAT is NOT a valid SMTP command.

The valid SMPT command would be "rcpt postmaster."

And as for the SPF record, as best I can tell, DNSCog has no knowledge of SPF records, only for "TEXT" record versions.

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I haven't had any problems with the output and testing against my own servers everything works correctly.

Have you yet checked the logs of your mail server? I'm expecting that you've got some form of filtering going on, possibly greylisting or possibly just simple firewalling.

The logs on my mail server indicate that DNScog has contacted it only once in the past 4 days. And that was on 27 December from "test@dnscog" Clearly nowhere near the number of times I have run the check -- Probably 2-3 times a day since then, after making changes to the zonefiles trying to figure out what it wants for various items

That suggests that they're having problems contacting your mail server, quite probably your entire system. I assume you don't normally have connectivity problems?

You may want to contrast the results with those from the likes of MX Toolbox, IntoDNS and Squishywishywoo (no, I'm not making that last one up!).

answered Dec 30 '10 at 03:10 PM

Cry Havok ♦
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WHMagill Dec 31 '10 at 08:16 PM

The logs on my mail server indicate that DNScog has contacted it only once in the past 4 days. And that was on 27 December from "test@dnscog"

Clearly nowhere near the number of times I have run the check -- Probably 2-3 times a day since then, after making changes to the zonefiles trying to figure out what it wants for various items.

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This may be due to greylisting by your mail server. Does the test handle greylisting?

answered Jun 10 '11 at 08:18 AM

gregb
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There are issues with DNScog which is why it says beta. Not all mail servers are configured the same.

Mine uses all available spam technologies. One of which beiong reverse dns lookups. DNScog fails with this since the ip the service runs from does not resolve to a host name therefore my mail server rejects the DNScog service for mail tests. Ironic isnt it?

See that issue here http://www.dyndnscommunity.com/questions/8090/dnscog-issue-semder-ip-must-resolve

I too experience duplicate addresses in dns for spf and others.

Like I said it is still beta. There are going to be issues. Reliable? That depends on how much you know about your own setup and how email works in detail to get what you need when using DNScog.

A much better service to use would be www.intodns.com

answered Jan 11 '11 at 11:36 AM