Why do some ports insist on make IPv6 connections?

[David O'Brien]

On systems running the GENERIC kernel (and thus having IPv6 enabled), two
ports that I know of run into trouble: ncftp3 and dillo.  For hosts that
have both IPv4 and IPv6 A[A] records:

    $ host ftp.vim.org
    ftp.nluug.nl has address 192.87.102.43
    ftp.nluug.nl has address 192.87.102.42
    ftp.nluug.nl has address 2001:610:1:80aa:192:87:102:42
    ftp.nluug.nl has address 2001:610:1:80aa:192:87:102:43

These apps insist on making IPv6 connections.  However, the only IPv6
routes I have is for lo0.  So I get errors like:

    Could not connect to ftp.vim.org: No route to host.

My question is why does this happen?  Why isn't the connection IPv4 given
I cannot get there from here [over IPv6]?

thanks,
-- 
-- David  (obrien at FreeBSD.org)