A couple of issues in here:
1. a copypasta incident meant that the v6 lookup was really just a v4
lookup. doh!
2. We would lookup v4 addresses and just be satisfied with those,
ignoring any v6 addresses
We now run the v4 and v6 lookups concurrently and merge the results
together.
We do still list the v4 addresses first in the list of addresses.
We don't try to be smart about using the "right" addresses when
work through the list; we try them all until one works out.
Correctly guessing at which one will work means replicating logic
in the kernel, and would potentially be screwed up when we add in
HAProxy support later.
This function returns MX information, including the computed site_name.
Update the queue example to show how to use it to populate the SITE_OF
map used in that example.
This commit switches to using the `Name` type under the covers to ensure
that we use canonical names for our cache keys.
Wez Furlong