Comment 4 for bug 1754358

You are right, I actually meant to go with

 server 0.ubuntu.pool.ntp.org iburst
 server 1.ubuntu.pool.ntp.org iburst
 server 2.ubuntu.pool.ntp.org iburst
 server 3.ubuntu.pool.ntp.org iburst

maxsources is only allowed on pools and servers are mostly like "pool maxsource 1".

I like the balanced approach you suggested.
We own ntp.ubuntu.com and if you recommend it I assume we are ok with getting all 4 of them.
I'd also add a comment why we do so, therefore my suggestion would be:

# This will use (up to) 4 sources from ntp.ubuntu.com which are ipv6 enabled
# It will further get (up to) 2 sources from 2.ubuntu.pool.ntp.org which is ipv6 enabled as well
# And further (up to) 1 source from [01].ubuntu.pool.ntp.org (ipv4 only atm)
# This means by default an overall of 6 ipv6/ipv4 and 2 more ipv4 only sources and at the same time some protection against one of the entries being down (compare to just using one of the lines). See (LP: #1754358) for the discussion.
 pool ntp.ubuntu.com iburst
 pool 0.ubuntu.pool.ntp.org iburst maxsources 1
 pool 1.ubuntu.pool.ntp.org iburst maxsources 1
 pool 2.ubuntu.pool.ntp.org iburst maxsources 2

Opinions on that?