[ietf-dkim] FW: draft-hallambaker-xptr-00

[Douglas Otis]

On Jun 29, 2007, at 11:12 AM, Hallam-Baker, Phillip wrote:

>
> I just submitted the attached as a personal Internet draft. It  
> describes the use of the XPTR record to provide generalized  
> discovery of wildcarded prefix records.

It seems that you should have included RFC 4592 as an informational  
reference.  This reference provides more illustrative examples of  
when wildcard synthesis is blocked when considering XPTR deployment.

The alternative to XPTR could be consistent use of discovery  
records.  This might be either SRV or MX records, for example. Valid  
non-existence could then be established in one fewer queries without  
wildcards or causing zones to expand.

Wildcards might also aid those attempting to stage some type of DNS  
based DDoS attack, which is fairly common.  A wildcard permits  
queries for RRs having the largest possible label and never answered  
from cache.  Add to that a scheme that even makes three additional  
queries based upon the initial query, and things get fairly depressing.

-Doug