IPv6 and NetworkManager
On most of the networks where I have hosts, the Ethernet interface has
an inet6 address with a 64 bit netmask and flags "scope global
noprefixroute dynamic."
On a Comcast Business network, though, my hosts have one inet6 address
with a 64 bit netmask and the same flags, plus another inet6 address
with a 128 bit netmask and flags "scope global dynamic."
Testing shows that these hosts use the address with the 128 bit netmask
by default as the source address for outbound connections.
I'm a little confused about the details here. Why are my hosts getting
multiple addresses with different prefixes?