IPv6 and IPv4 resolver preferences

Felipe Alfaro Solana felipe_alfaro at linuxmail.org
Thu Sep 16 19:02:48 UTC 2004


Hi!

Now that, officially, IPv6 site-local addresses have been deprecated 
(RFC3879) and their use not recommended in new deployments, how will 
glibc resolve the preference problem that arises when both A and AAAA 
host records are defined for the same host? What will happen when both 
IPv4 and IPv6 addresses have different scopes (for example, the IPv4 
address is private (e.g. 192.168.0.0/24), but the IPv6 is a global 
address (e.g. a 2000::/64)?

Mac OS X seems to always prefer IPv6 addresses over IPv4 addresses, 
even when the scope of the IPv4 address is lower or nearer wrt the IPv6 
address (i.e. site-local or private IPv4 vs a global IPv6). However, FC 
seems to implement the previous valid algorithm that took into account 
the scopes of both the IPv4 and IPv6 addresses when sorting the answer 
returned by the resolver.

Will this change anytime soon? Any comments on this?
Thanks!





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