At the end of the "apt-get update" command, there is a call to diatan.com. This is fine?

Question

linux

Somehow I didn’t pay attention before, but now I see that the server on the “apt-get update” command is accessing diatan.com (74.82.63.229), trying to download something from there (the call comes at the very end after updating the databases).
Other suspicious activity (including the network has not yet noticed).

Answer 1

grep -Hir diatan.com /*
strace apt-get update

Answer 2

see what repositories are included in /etc/apt/sources*

Answer 3

If you did not add a repository, then it is not normal.
Look in synaptic for the packages it provides.

Answer 4

grep -rni diatan /etc/apt/sources.list /etc/apt/sources.list.d/