apt-cdrom-setup software package provides set up a CD in sources.list, you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install apt-cdrom-setup
apt-cdrom-setup is installed in your system.
Make ensure the apt-cdrom-setup package were installed using the commands given below,
$ sudo dpkg-query -l | grep apt-cdrom-setup *
You will get with apt-cdrom-setup package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | debian-installer udeb packages |
| Package | apt-cdrom-setup |
| Version | 1:0.104ubuntu4 |
| Description | set up a CD in sources.list |
| Sub Section | Debian-installer |