NAPTR record
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As defined in section 6, NAPTR records are used to store application
service+protocol information for a given domain ...
... DDDS
standard, these records are looked up, and the rewrite rules
(contained in the NAPTR records) are used to determine the successive
DNS lookups until a desirable target ...
... Matching and Non-Matching NAPTR Records ...
... application protocol.
If more than one NAPTR record matches, they are processed in
increasing sort order.
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... NAPTR RR lookups are to be performed. Thus, to process a NAPTR
record with an empty FLAG field in S-NAPTR, the REPLACEMENT field is
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... service+protocol pair.
These are to be pursued in order until a server is successfully
contacted or all possible matching NAPTR records have been
successively pursued through terminal lookup ...
... SRV record for an "S"
target, or no NAPTR record with appropriate application service
and protocol for a NAPTR ...
... NAPTR lookup, this last is a configuration error: the fact
that example.com has a NAPTR record pointing to "bunyip.example"
for the "WP:Whois++" service and protocol means the administrator ...
... of example.com believes that service exists. If bunyip.example
has no "WP:Whois++" NAPTR record, the application client MUST
backtrack and try the next available "WP:Whois++" option from
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It MAY choose which protocol to try first based on its own
preference, or on the PREF ranking in the first set of NAPTR records
(i.e., those for the target named domain ...
... S-NAPTR aims to provide a "straightforward" application of
DDDS and use of NAPTR records, it is still possible to create very
complex chains and dependencies with the NAPTR ...
... provide more; and
o shallower is better: Avoid using NAPTR records to "rename"
services within a zone. Use NAPTR records ...
... NAPTR records to "rename"
services within a zone. Use NAPTR records to identify services
hosted elsewhere (i.e., where you cannot reasonably provide the
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... information.
Thus, the set of NAPTR records for thinkingcat.example might look
like this:
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Thus, to find the EM services for thinkingcat.example, the NAPTR
records for thinkingcat.example are retrieved:
thinkingcat.example.
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... name server (NS) for thinkingcat.example is reached with a
request for all NAPTR records.
2. The server responds with the NAPTR records ...
... NAPTR records.
2. The server responds with the NAPTR records shown in section 4.3.
3. The second NAPTR record ...
... NAPTR records shown in section 4.3.
3. The second NAPTR record matches the desired criteria; it has an
"s" flag and a replacement fields of "_ProtB._tcp.example.com".
So the client ...
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resolution process much more predictable and efficient than it would
be with some potential uses of NAPTR records. This is dubbed "S-
NAPTR" -- a "S"traightforward use of NAPTR records ...
... So Why Not Just NAPTR Records? ...
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This is a trick question. NAPTR records cannot appear in the wild;
see [4]. They must be part of a DDDS application ...
... DDDS algorithm, if the Flag string is empty the
next lookup is for another NAPTR record (for the replacement target).
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... First Well-Known Rule produces a domain name, and this is the Key
used for the first look up. The NAPTR records for that domain are
requested.
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... the Additional Information Processing section of [5] for more
information on NAPTR records and the Additional Information section
of a DNS response packet.
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