On Thu, Sep 13, 2007 at 07:43:38PM +0100, Tony Finch wrote: > On Thu, 13 Sep 2007, David Conrad wrote: > > > > How do you renumber the IP address stored in the struct sockaddr_in in a > > long running critical application? > > Applications that don't respect DNS TTLs are broken for many reasons, not > just network renumbering. > > Tony. I know of one application that relied on long-lived DNS hostname to IP mappings and ignored DNS TTLs. Search engine crawlers cached the IP addresses for pages that had been fetched, and used those addresses even though the TTLs had expired. This resulted in pages from whatever content lived at those new IP addresses showing up unexpectedly (incorrectly) in search engine results. I don't know if this has been fixed, but it's an example of application usage that bypassed IETF recommendations for a presumably good cause (performance reasons). Another application with a similar reliance that is seeing some growth is the use of IP addresses for geotargeting. The geotargeting provider attempts to determine the physical location of the IP address for various purposes, such as to choose what ads to display. I imagine people on this list can see the flaws of doing this, but nevertheless it persists. I don't know how the geotargeting providers plan to handle IPv6, but it's another example of how people develop applications in ways that the IETF may not anticipate (because they discourage such applications), but make migration to IPv6 difficult because of the installed base that depends upon specific uses of IPv4 addresses. --gregbo _______________________________________________ Ietf@xxxxxxxx https://www1.ietf.org/mailman/listinfo/ietf