ipv6 apt issue

Greetings,

I'm hitting an IPv6 snafu.

I've got a dual stack host and when doing various apt-y things I attempt to connect to:

# apt update

0% [Connecting to ftp-chi.osuosl.org (2600:3402:200:227::2)

but it hangs and doesn't seem to complete its connection.

If I look at my sources lists:

% grep http /etc/apt/sources.list.d/*.list | sed -e 's/.*http:\/\///' | uniq

ftp.us.debian.org/debian/ jessie main contrib non-free

ftp.us.debian.org/debian/ sid main contrib non-free

ftp.us.debian.org/debian/ stretch main contrib non-free

I don't have an /etc/apt/sources.list file. To my observation, my host should only be connecting ftp.us.debian.org.

Which has the following v6 addresses:

% dig ftp.us.debian.org aaaa +short

2610:148:1f10:3::89

2620:0:861:1:208:80:154:15

So, where does the above ftp-chi.osuosl.org (2600:3402:200:227::2) coming from?

Thanks for any pointers!

-m