lst_ho...@kwsoft.de:
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> Zitat von Wietse Venema <wie...@porcupine.org>:
>
> > lst_ho...@kwsoft.de:
> >> Hello
> >>
> >> we are on the way to IPv6 and some question arise about Postfix IPv6
> >> behaviour in dual stack setup.
> >
> > You mean dual-protocol. Unlike some versions of Linux, there exist
> > systems that have a single unified TCP/IP stack implementation (the
> > protocols have a fair amount of behavior in common).
>
> Sorry for being imprecise. Most of talk in IPv6 is about dual-stack so
> i adopted it without thinking twice about the technical details...
>
> >> 1.) Do the lookups for AAAA when resolving MX records occur in
> >> parallel to A queries, or is some additional latency expected due to
> >> the fact that many AAAA queries fail by timeout and others resolving
> >> errors?
> >
> > With smtp_host_lookup=dns, all SMTP client lookups are sequential.
> > With smtp_host_lookup=native (or dns,native) Postfix in dual-protocol
> > mode will invoke getaddrinfo() with hints.ai_family=PF_UNSPEC.
> > The internals of getaddrinfo() are system dependent.
>
> From what i can see i don't want "smtp_host_lookup=native" for
> potential side-effects, but do i get it right that it is still unsure
> if the lookup is done in parallel or not when using "native"?
That is operating system dependent.
> >> 2.) Do AAAA/ip6.arpa lookup occur on client connects from IPv4
> >> addresses or only when a client connects by IPv6 (name/reverse lookups)?
> >
> > The Postfix SMTP server's FCRDNS lookups use the getnameinfo() and
> > getaddrinfo() system library functions. In dual-protocol mode,
> > Postfix invokes getaddrinfo() with hints.ai_family=PF_UNSPEC; it
> > would be smarter to pass the client's address family instead.
>
> So it is suspected to change some day, but as of now dependant on the
> OS/nsswitch.conf used?
That is also operating system dependent.
Wietse
