[antispam-f] Re: DNS problems
- From: Frank de Bruijn <antispam@xxxxxxxxx>
- To: antispam@xxxxxxxxxxxxx
- Date: Mon, 20 May 2013 19:27:20 +0200
In article <534ed834f5freelists@xxxxxxxxxxxxxxxx>,
Martin <freelists@xxxxxxxxxxxxxxxx> wrote:
> > Indeed. Hard to tell why, but it appears the nameserver involved
> > doesn't answer the query.
> Do you have an example of what it could be doing,
Not really. I've never seen it happen before. I'll check if there is an
easy way to shorten the time outs when I have my current hardware
problems sorted out [1].
Did you try another nameserver to check if it is indeed a problem with
your default one?
> and a way to perform the query RISC OS and on Windows? Then I could
> check it still does not work, and if not report it to my ISP!
Blocklist lookups are simply DNS requests of 'pseudo hostnames' on a
particular zone. The nameserver you're using is supposed to handle
forwarding of the query if it can't provide the answer itself.
An example. Assuming you want to know if IP address 1.2.3.4 is in
SpamHaus's zen list, you send the nameserver a request to provide the IP
address of the host 4.3.2.1.zen.spamhaus.org. If it comes back as
unknown ('NXDOMAIN'), it is not listed. If the answer is an address in
the localhost/loopback range (i.e. 127.X.X.X) the address tells you in
which list it is (see the Settings file in !Antispam.Resources.!NSQ for
details).
On Windows and Linux, you can use the nslookup tool to check this
manually. On RISC OS you need a tool like NSQ that bypasses the default
resolver, because that is broken and assumes anything starting with a
dotted quad (e.g. 4.3.2.1) is a 'normal' reverse lookup so the zone gets
stripped off.
Regards,
Frank
[1] Iyonix lost it's network interface - PSU problems again, most
likely. Linux box with RPCEmu (where I'm writing this) keeps forgetting
it has a keyboard. I *really* need some new hardware... :-(
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