IP address
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For the first aspect, proxy 1 specifically needs to determine the IP
address, port, and transport protocol for the server in domain ...
... client) may need to perform DNS
processing to determine the IP address, port, and transport protocol
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... URI is not rewritten with the
result of the DNS lookup), they only result in an IP address, port
and transport protocol ...
... proxy not identified by a SIP URI, but rather,
by a hostname or numeric IP address. In that case, a temporary URI,
used for purposes of this specification, is constructed. That URI ...
... proxy>, where <proxy> is the FQDN or numeric IP
address of the next-hop proxy. As a result, in all cases, the
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... We determine the transport protocol, port and IP address of a
suitable instance of TARGET in Sections 4.1 and 4.2.
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... transport protocol is specified, but the TARGET is a
numeric IP address, the client SHOULD use UDP for a SIP URI ...
... port is specified, and the
target is not a numeric IP address, the client SHOULD perform a NAPTR
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... Determining Port and IP Address ...
... Once the transport protocol has been determined, the next step is to
determine the IP address and port.
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... AAAA record lookup of the domain
name. The result will be a list of IP addresses, each of which can
be contacted at the specific port from the URI ...
... lookup of the domain name. The result will be a list of IP
addresses, each of which can be contacted using the transport
protocol determined previously, at the default port for that
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... In these cases, the server examines the value of the sent-by
construction in the topmost Via header. If it contains a numeric IP
address, the server attempts to send the response to that address,
using the transport protocol ...
... tries to send the response to each element on the resulting list of
IP addresses, using the port from the Via, and the transport protocol
...
... property that they resolve to the specific element that inserted
them. However, if they are constructed with just an IP address, for
example:
...
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SRV provides a way to fix this. Instead of using an IP address, a
domain name that resolves to an SRV record ...