Re: interop problems with getaddrinfo() address selection

[Tony Finch <[e-mail]>]

On Mon, 10 Dec 2007, der Mouse wrote:
>
> But whose definition of "equivalent" applies?  From a client point of
> view, close addresses are not equivalent to distant addresses - the
> client wants a nearby server, not unreasonably - making sorting by
> match length at least moderately reasonable.

In practice, services advertise server-specific names as well as umbrella
names, so that clients that care about which server they use can ask for
it.

> Any architecture that depends on the DNS preserving record ordering
> (never mind depending on clients doing anything in particular with the
> order the DNS happens to give them) is already broken.

Services that use round robin DNS do not depend on preserved record
ordering: quite the opposite, they depend on disordering. (Bind does
round-robin when acting as a cache as well as an authoritative server.)
You can claim it's broken until you are blue in the face, but it works in
practice and it is widely documented (though not by the IETF) without
caveats.

Tony.
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