On 2007-07-17 11:04, michael(_dot_)dillon(_at_)bt(_dot_)com wrote:
it is not reasonable to assume that for all apps the correct
model is to do a DNS lookup and then try the resulting IP
addresses one at a time until a connection succeeds for one of them.
For instance, applications in the global finance industry typically do
not do any DNS lookups at all. Admittedly, they often have a list of
destination IP addresses which they try until a connection succeeds. But
the point is that IPv6 transition has to be explicitly programmed into
each and every application and it has to be embedded in the operational
processes as well.
Which is in fact the exact same logic a dual stack application should
follow after calling getaddrinfo(). Whether or not you resolve a name
to get the list of addresses, you need the logic to try all available
addresses in turn.
otoh, I've never yet found an application programmer who found upgrading
to the new socket API to be especially challenging; it's just work.
As Michael says, it has to be done for each application.
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