NAPTR
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The character set used to specify the various values of the NAPTR
records is UTF-8 [17]. Care must be taken to ensure that, in the
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... client
issues a request, following standard DNS rules, for NAPTR Resource
Records for the given domain-name.
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... The response to a request for a given Key (domain-name) will be a
series of NAPTR records. The format of a NAPTR Resource Record
can be found in Section 4.
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... domain-name) will be a
series of NAPTR records. The format of a NAPTR Resource Record
can be found in Section 4.
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... URI Resolution Applications,
Section 6.2), there is a chance of collision between rules where
two NAPTR records appear in the same domain but they apply to more
than one Application. There are three ways to avoid collisions:
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... create a new zone within the domain in common that contains
only NAPTR records that are appropriate for the application.
E.g., all URI Resolution records would exist under
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The packet format for the NAPTR record is as follows
1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
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... A 16-bit unsigned integer specifying the order in which the NAPTR
records MUST be processed in order to accurately represent the
ordered list of Rules. The ordering is from lowest to highest.
If two records have the same order value then they are considered
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... bit unsigned integer that specifies
the order in which NAPTR records with equal Order values SHOULD be
processed, low numbers being processed before high numbers. This
is similar to the preference field in an MX record, and is used so
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... by the client, never to the
domain name produced by a previous NAPTR rewrite. The latter is
tempting in some applications but experience has shown such use to
be extremely fault sensitive, very error prone, and extremely
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... 15]. This
example details how a particular URN would use the NAPTR record to
find a resolver service that can answer questions about the URN ...
... client queries the DNS for NAPTR records for the domain-
name 'cid.urn.arpa'. The result is a single record:
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... service regexp replacement
IN NAPTR 100 10 "" "" "!^urn:cid:.+@([^\.]+\.)(.*)$!\2!i" .
Since there is only one record, ordering the responses is not a
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... domain. While all hosts, such as 'bar', could have their very own
NAPTR, maintaining those records for all the machines at a site could
be an intolerable burden. Wildcards are not appropriate here since
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... ;; order pref flags service regexp replacement
IN NAPTR 100 50 "a" "z3950+N2L+N2C" "" cidserver.example.com.
IN NAPTR 100 50 "a" "rcds+N2C" "" cidserver.example.com.
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... NAPTR 100 50 "a" "z3950+N2L+N2C" "" cidserver.example.com.
IN NAPTR 100 50 "a" "rcds+N2C" "" cidserver.example.com.
IN NAPTR 100 50 "s" "http+N2L+N2C+N2R" "" www.example.com.
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... NAPTR 100 50 "a" "rcds+N2C" "" cidserver.example.com.
IN NAPTR 100 50 "s" "http+N2L+N2C+N2R" "" www.example.com.
Continuing with the example, note that the values of the order and
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... "2.1.2.1.5.5.5.0.7.7.1.e164.arpa.". This domain-name is then used to
retrieve Rewrite Rules as NAPTR records.
For this example telephone number ...
... ORIGIN 2.1.2.1.5.5.5.0.7.7.1.e164.arpa.
IN NAPTR 100 10 "u" "sip+E2U" "!^.*$!sip:information@foo.se!i" .
IN ...
... E2U" "!^.*$!sip:information@foo.se!i" .
IN NAPTR 102 10 "u" "smtp+E2U" "!^.*$!mailto:information@foo.se!i" .
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A client MUST process multiple NAPTR records in the order specified
by the "order" field, it MUST NOT simply use the first record that
provides a known Service Parameter ...
... equal, the client should use the value of the preference field to
select the next NAPTR to consider. However, because it will often be
the case where preferred protocols or services exist, clients ...