DNS Lookups
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... SIP trapezoid
It is important to note that DNS lookups can be used multiple times
throughout the processing of a call. In general, an element that
...
... caller initiates a call until the time the called party is
alerted should be no more than a few seconds. Given that there can
be multiple hops, each of which is doing DNS lookups in addition to
other potentially time-intensive operations, the amount of time
available for DNS lookups ...
... DNS lookups in addition to
other potentially time-intensive operations, the amount of time
available for DNS lookups at each hop is limited.
Scalability ...