lookup
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... (contained in the NAPTR records) are used to determine the successive
DNS lookups until a desirable target is found.
...
... more NAPTR RR lookups are to be performed. Thus, to process a NAPTR
record with an empty FLAG field in S-NAPTR ...
... S-NAPTR, the REPLACEMENT field is
used as the target of the next DNS lookup -- for NAPTR RRs.
...
... NAPTR records have been
successively pursued through terminal lookup and server contact.
That is, a client must backtrack and attempt other resolution paths
...
...
o the S-NAPTR-designated DNS lookup fails to yield expected results
-- e.g., no A RR for an "A" target ...
... lookup. Except in the case of the very
first NAPTR lookup, this last is a configuration error: the fact
that example.com has a NAPTR record pointing to "bunyip.example"
...
... resolution completely for one protocol, exploring all potential
terminal lookups in PREF and ORDER ranking, until the application
connects successfully or there are no more possibilities for that
protocol.
...
... SRV records; each SRV record points to several A record lookups.
Even though a particular client can "prune ...
... layer of indirection; the outcome of an SRV
lookup is a new domain name for which the A RR is to be found.
...
... domains. We could tweak SRV
to say that the next lookup could be something other than an address
record, but this is more complex than is necessary for most
...
...
Both are for terminal lookups. This means that the Rule is the last
one and that the flag determines what the next stage should be. The
"S" flag means that the output of this Rule is a domain ...
... 3] records exist. "A" means that the output
of the Rule is a domain name and should be used to lookup address
records for that domain ...
... Consistent with the DDDS algorithm, if the Flag string is empty the
next lookup is for another NAPTR record (for the replacement target).
...
...
o entwine the application-specific protocol with the DNS lookup and
RRset processing described in the pseudocode ...