Subject: question about "what is a legal name?"

From: Edward Lewis <[email-masked]>
Date: Tue, 1 Jun 2004 09:27:11 -0400

In the MARID WG, there is consideration being given to names such as 
the following:

    _marid.*.foo.com.

I've been saying that the name above is not legal, based on the words 
in RFC 1034, section 4.3.3 that define wild cards.  One answer I have 
received is that the above name is not a wild card, hence the 
restrictions that no "*" appear in the <domain> there is not valid.

I'd like to hear from others on this, whether the above name is legal 
or not, whether there is an interoperability issue stemming from the 
the lack of clarity in the documents.

Here's my take.  Looking at the tree of labels, I'm going to add 
a.foo.com and c.foo.com, leaving b.foo.com out.

           .
           |
          com
           |
          foo--------------------
           |     |             |
           *     a(.foo.com)   c(.foo.com)
           |
        _marid

What happens when a query arrives for b.foo.com?

I think the intent in the specs is to not use *.foo.com. as a "wild 
card".  From the definition of a wild card as "*.<domain without *>", 
I think the server ought not synthesize from that record.  This 
implies that the algorithm of "find the closest encloser, which is 
foo.com, and use the '*' labelled child for synthesis" has to be 
amended to watch out for '*' with children.

Another issue I can see of permitting such names is to start with 
just "*.foo.com." and not the "_marid" label.  Assuming the 
administrator is expecting "*.foo.com." to be a wild card, what 
happens when some one adds, via dynamic update, the label "_marid" 
below that domain?  Should this addition be barred from dynamic 
update?

These are two "corner cases" that arise from mid-tree * labels. 
Perhaps implementors feel that there's a way around this by adding 
flag bits on the labels or by implementing more rules for processing, 
but my *opinion* is that such names ought to be considered bad ju-ju.

(Note: I'm neglecting the "why" of even thinking of such a name.)
-- 
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Edward Lewis                                            +1-703-227-9854
ARIN Research Engineer

Even the voices inside my head are refusing to talk to me anymore.

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