spf-discuss
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Wildcard DNS entry

2004-09-09 00:18:00
Meng Weng Wong wrote:

Yeah, there are four classes of solutions, really.

1) deprecate "implicit mx"
2) modify spec to allow searching up the tree, as Wayne has
   proposed in the past
3) put an SPF record on each host
4) encourage the world to assume "a/24 mx/24 ptr -all" for
   non-publishing domains

Fifth solution:

In the DNS server software implement a new wildcard with the meaning
"Use this RR if there is no RR of the same type and only if the subdomain
exists (has other RRs)".

The advantage is that only the site that publish such a wildcard has to
change anything.

For example:

watkins-home.com.       txt     "v=spf1 ..."
**.watkins-home.com.    txt     "v=spf1 -all"
www.watkins.home.com.   a       1.2.3.4

Querying www.watkins.home.com would return "v=spf1 -all" and querying
xyz.watkins.home.com would return NXDOMAIN.

Roger