Need to confirm the action for each of these scenerios.

IPv4 ONLY node
==============

For a ipv4 only target address:
rsync       : Uses v4 address, as expected. PASS
rsync -4    : Uses v4 address, as expected. PASS
rsync -6    : Uses v4 address. PASS

For a ipv6 only target address:
rsync       : Name or service not known, as expected. FAIL
rsync -4    : Name or service not known, as expected. FAIL
rsync -6    : Name or service not known, as expected. FAIL

For a mixed v4/v6 target address:
rsync       : Uses v4 address, as expected. PASS
rsync -4    : Uses v4 address, as expected. PASS
rsync -6    : Uses v4 address, as expected. PASS


IPv6 ONLY node
==============

For a ipv4 only target address:
rsync       : 
rsync -4    :
rsync -6    :

For a ipv6 only target address:
rsync       :
rsync -4    :
rsync -6    :

For a mixed v4/v6 target address:
rsync       :
rsync -4    :
rsync -6    :

Mixed v4/v6 node
================

For a ipv4 only target address:
rsync       : Uses v4 address, as expected. PASS
rsync -4    : Uses v4 address, as expected. PASS
rsync -6    : Name or service not known, as expected. FAIL

For a ipv6 only target address:
rsync       : Uses v6 address, as expected. PASS
rsync -4    : Name or service not known, as expected. FAIL
rsync -6    : Uses v6 address, as expected. PASS

For a mixed v4/v6 target address:
rsync       : Uses v6 address, as expected. PASS
rsync -4    : Uses v4 address, as expected. PASS
rsync -6    : Uses v6 address, as expected. PASS

Mixed v4/v6 node with broken v6 poublic route
=============================================
<not tested>