DNS
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... Working Group [3] as a way
to encode rule-sets in DNS so that the delegated sections of a URI
could be decomposed in such a way that they could be changed and re-
...
... Regular expressions were chosen
for their compactness to expressivity ratio allowing for a great deal
of information to be encoded in a rather small DNS packet.
...
... be the first well known key (<something>.uri.arpa for example) or
a new key that is the output of a replacement or regexp rewrite.
Beyond this, it has the standard DNS requirements [1].
...
... an A, AAAA, or A6 record. The "U" flag means that the next step
is not a DNS lookup but that the output of the Regexp field is an
URI that adheres to the 'absoluteURI' production found in the
...
... this case is determined elsewhere.
DNS servers MAY interpret these flags and values and use that
information to include appropriate SRV and A,AAAA ...
... SRV and A,AAAA, or A6 records
in the additional information portion of the DNS packet. Clients
are encouraged to check for additional information but are not
...
... The result of applying the substitution expression to the original
URI MUST result in either a string that obeys the syntax for DNS
domain-names [1 ...
... such that a non-conforming domain-name can be constructed, client
software SHOULD verify that the result is a legal DNS domain-name
before making queries ...
... client would
construct the domain-name _http._tcp.somedomain.com and ask the DNS
if that records exists. The underscores are used to avoid collisions
with potentially 'real' domain ...
... DNS Packet Format ...
... Advice for DNS Administrators ...
... regular expressions. Not only are they difficult to get
correct on their own, but there is the previously mentioned
interaction with DNS. Any backslashes in a regexp must be entered
twice in a zone file in order to appear once in a query response.
...
... More seriously, the need for double backslashes has probably not been
tested by all implementors of DNS servers.
...
... Gulbrandsen, A., Vixie, P. and L. Esibov, "A DNS RR for specifying the location of services (DNS SRV ...