Matthew Elvey <matthew(_at_)elvey(_dot_)com> wrote:
PS Could someone clarify the purpose of the Ignore Target bit?
I don't get it from the definition: The domain name in the Target field
is a placeholder, and any IP addresses it resolves to MUST NOT be used
for authentication.
This is the wording the authors finally agreed upon. (I dread the
thought of changing it, but I suppose we could add some words to clarify.)
The field was earlier named "empty list". The whole point is that there
will be cases where the empty list is intended. It turns out that problems
have been observed by DNS experts where implementations of SRV actually
query for the "." <single-dot> domain-name (in violation of the spec),
and this has caused useless traffic on the root-servers.
By request of DNS experts, we specified the use of the Name portion of
the QNAME as a placeholder when the empty-list is intended, along with
the setting of this bit to indicate the name. (There may still be broken
implementations, but they won't harm the root-servers.)
--
John Leslie <john(_at_)jlc(_dot_)net>