Hello genlemen,
I am new here; I am a postmaster and sysadmin for a major ISP in my
country, and a programmer (mostly open source). Lately, we are doing
rather active antispam R&D and that's why I subscribed to this maillist.
On Tue, 2004-02-10 at 22:01, Yakov Shafranovich wrote:
Walter Dnes wrote:
On Mon, Feb 09, 2004 at 03:30:17PM -0500, Yakov Shafranovich wrote
All of this implies that reputation services such as blacklists will
continue to exist. However, a major problem has been with these services
is that they provide a binary yes/no answer.
There is no inherent binary limitation of today's de-facto DNSbl
implementations. DNSbls have have approximately 16 million possible
responses in the 127.0.0.0/8 CIDR. And furthermore, they can return
multiple records for one query (which is the querying software's
responsibility to handle properly). Quite a few DNSbls have an
"aggregate zone", which can return multiple multiple values.
What bothers me is that these codes vary from list to list. Would a
standard set of codes help?
Second problem that I have is the use of 127.xxx IP addresses for this.
This is really not something that should be done via IP addresses, a
custom SRV, RR or TXT record would server a much better purpose.
This decision of dnsbl maintainers to use 'A' RRs has always made me
feel uneasy. Given that the search key is a reverse dotted quad IP
address, it seems quite logical to use 'PTR' RR, which would give you
alphanumeric namespace for the return codes. Or TXT or any other: 'A'
seems the least suitable of all.
I think that if a dnsbl standard is ever proposed, it sould not use 'A'
RRs. Maybe TXT would be best, as they allow more flexible syntax, like
that used by SPF.
[if I am not supposed to post here not being an asrg member, tell me]
Regards
Eugene
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