SRV
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... DNS resource records. This can be
viewed as a more general version of the use of SRV and/or a very
restricted application of the use of NAPTR resource records.
...
... SRV RRs,
and normal SRV processing is applied. In the case of an "A" flag, an
address record is sought for the REPLACEMENT field target ...
... S-NAPTR is to provide application standards developers
with a more powerful framework (than SRV RRs alone) for naming
service ...
... possible to create very
complex chains and dependencies with the NAPTR and SRV records.
Therefore, domain ...
... RR that is retrieved points to more NAPTR or
SRV records; each SRV record points to several A record lookups ...
...
o fewer branches is better: For both NAPTR and SRV records, provide
different targets with varying preferences where appropriate
...
... services
hosted elsewhere (i.e., where you cannot reasonably provide the
SRV records in your own zone).
...
... service. See section 4.4 for an example that cannot be served by
SRV records alone.
...
... service, yet the out-sourcer can independently
rank the preference and ordering of servers. This independence is
not achievable through the use of SRV records alone.
Thus, to find the EM services ...
... SRV 20 0 10001 backup.em.example.com.
IN SRV 30 0 10001 nuclearfallout.australia-isp.example.
...
... SRV 20 0 10001 backup.em.example.com.
IN SRV 30 0 10001 nuclearfallout.australia-isp.example.
...
... "s" flag and a replacement fields of "_ProtB._tcp.example.com".
So the client looks up SRV records for that target, ultimately
making the request of the NS ...
... NS for example.com.
4. The response includes the SRV records listed in Section 4.3.
5. The client ...
... 5. The client attempts to reach the server with the lowest PREF in
the SRV list -- looking up the A record for the SRV record's
...
...
7. The client attempts to reach the second server in the SRV list
and looks up the A record for backup.em.example.com.
...
... IP address, on port 10001 (from the
SRV record), by using ProtB over tcp.
10. The server responds with an "OK" message.
...
... identify server targets and stipulate that clients should look up SRV
resource records to determine the host ...
... inherent limitations.
That is, although SRV records can be used to map from a specific
service name and protocol for a specific domain ...
... service name and protocol for a specific domain to a specific server,
SRV records are limited to one layer of indirection and are focused
on server administration rather than on application naming.
...
... multiple levels of redirection before the target server machine with
an SRV record is located, this proposal requires only a subset of
NAPTR strictly bound to domain names ...
... So Why Not Just SRV Records? ...
...
An expected question at this point is: this is so similar in
structure to SRV records, why are we doing this with DDDS/NAPTR?
...
... SRV include the following:
o SRV provides a single layer of indirection; the outcome of an SRV
...
... o SRV provides a single layer of indirection; the outcome of an SRV
lookup is a new domain name ...
... RR is to be found.
o the purpose of SRV is to address individual server administration
issues, not to provide application naming: As stated in [3 ...
... issues, not to provide application naming: As stated in [3], "The
SRV RR allows administrators to use several servers for a single
domain, to move services ...
... for the uses described here.
The basic answer is that SRV records provide mappings from protocol
names to host and port ...
... service label to servers that may in be
hosted within different administrative domains. We could tweak SRV
to say that the next lookup could be something other than an address ...
... "S" flag means that the output of this Rule is a domain label for
which one or more SRV [3] records exist. "A" means that the output
of the Rule is a domain name ...
... DNS servers MAY interpret Flag values and use that information to
include appropriate NAPTR, SRV, or A records in the Additional
Information portion of the DNS packet ...
... DNS queries along the way. If any of
them is compromised, bogus NAPTR and SRV records could be inserted to
redirect clients to unintended destinations ...
... transformations that may have resulted from NAPTR replacements,
SRV targets, or CNAME changes). In certain cases where the
...